Thanks for the issue...

Tried to reproduce the issue on reported chrome version 70.0.3538.77 using Mac 10.14. Attaching screenshot for reference.
Steps: 
---------
0. Launched chrome and enabled hardware acceleration
1. opened https://jsfiddle.net/m7t1yvrd/12/
2. observed the image the shadow is on the right side and bottom of the image
As we have not seen clipped.

@Reporter: Could you please check the attached screenshot and please let us know if anything missed from our end.

Thanks..!

Deleted: 899512.png 450 KB

	899512.png 450 KB View Download

To me looks different, check my screenshot.
Sometimes the first render is OK, other time is broken from the start.
To me looks an HW acceleration issue.
The problem goes away if you disable chrome hw acceleration

Deleted: Screen Shot 2018-10-29 at 4.21.47 PM.png 875 KB

	Screen Shot 2018-10-29 at 4.21.47 PM.png 875 KB View Download

Thank you for providing more feedback. Adding the requester to the cc list.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Could you please attach your chrome://gpu ?

The NextAction date has arrived: 2018-11-12

Graphics Feature Status
Canvas: Hardware accelerated
Flash: Hardware accelerated
Flash Stage3D: Hardware accelerated
Flash Stage3D Baseline profile: Hardware accelerated
Compositing: Hardware accelerated
Multiple Raster Threads: Enabled
Native GpuMemoryBuffers: Hardware accelerated
Out-of-process Rasterization: Disabled
Hardware Protected Video Decode: Unavailable
Rasterization: Hardware accelerated
Skia Deferred Display List: Disabled
Skia Renderer: Disabled
Surface Synchronization: Enabled
Video Decode: Hardware accelerated
Viz Service Display Compositor: Disabled
WebGL: Hardware accelerated
WebGL2: Hardware accelerated
Driver Bug Workarounds
adjust_src_dst_region_for_blitframebuffer
avoid_stencil_buffers
decode_encode_srgb_for_generatemipmap
disable_2d_canvas_auto_flush
disable_framebuffer_cmaa
dont_use_loops_to_initialize_variables
get_frag_data_info_bug
pack_parameters_workaround_with_pack_buffer
regenerate_struct_names
remove_invariant_and_centroid_for_essl3
scalarize_vec_and_mat_constructor_args
set_zero_level_before_generating_mipmap
unfold_short_circuit_as_ternary_operation
unpack_alignment_workaround_with_unpack_buffer
use_intermediary_for_copy_texture_image
use_unused_standard_shared_blocks
disabled_extension_GL_KHR_blend_equation_advanced
disabled_extension_GL_KHR_blend_equation_advanced_coherent
Problems Detected
Protected video decoding with swap chain is for Windows and Intel only
Disabled Features: protected_video_decode
Unfold short circuit on Mac OS X: 307751
Applied Workarounds: unfold_short_circuit_as_ternary_operation
Always rewrite vec/mat constructors to be consistent: 398694
Applied Workarounds: scalarize_vec_and_mat_constructor_args
Mac drivers handle struct scopes incorrectly: 403957
Applied Workarounds: regenerate_struct_names
glGenerateMipmap fails if the zero texture level is not set on some Mac drivers: 560499
Applied Workarounds: set_zero_level_before_generating_mipmap
Pack parameters work incorrectly with pack buffer bound: 563714
Applied Workarounds: pack_parameters_workaround_with_pack_buffer
Alignment works incorrectly with unpack buffer bound: 563714
Applied Workarounds: unpack_alignment_workaround_with_unpack_buffer
copyTexImage2D fails when reading from IOSurface on multiple GPU types.: 581777
Applied Workarounds: use_intermediary_for_copy_texture_image
Use GL_INTEL_framebuffer_CMAA on ChromeOS: 535198
Applied Workarounds: disable_framebuffer_cmaa
glGetFragData{Location|Index} works incorrectly on Max: 638340
Applied Workarounds: get_frag_data_info_bug
Decode and encode before generateMipmap for srgb format textures on macosx: 634519
Applied Workarounds: decode_encode_srgb_for_generatemipmap
Insert statements to reference all members in unused std140/shared blocks on Mac: 618464
Applied Workarounds: use_unused_standard_shared_blocks
adjust src/dst region if blitting pixels outside read framebuffer on Mac: 644740
Applied Workarounds: adjust_src_dst_region_for_blitframebuffer
Mac driver GL 4.1 requires invariant and centroid to match between shaders: 639760, 641129
Applied Workarounds: remove_invariant_and_centroid_for_essl3
Disable KHR_blend_equation_advanced until cc shaders are updated: 661715
Applied Workarounds: disable(GL_KHR_blend_equation_advanced), disable(GL_KHR_blend_equation_advanced_coherent)
Certain Apple devices leak stencil buffers: 713854
Applied Workarounds: avoid_stencil_buffers
Shader variable initialization in a loop caused perf regression on Mac Intel.: 809422
Applied Workarounds: dont_use_loops_to_initialize_variables
glFlush error on Mac: 841755
Applied Workarounds: disable_2d_canvas_auto_flush
Viz service display compositor is not enabled by default.
Disabled Features: viz_display_compositor
Skia renderer is not used by default.
Disabled Features: skia_renderer
Skia deferred display list is not used by default.
Disabled Features: skia_deferred_display_list
Version Information
Data exported	2018-11-12T12:29:45.551Z
Chrome version	Chrome/70.0.3538.102
Operating system	Mac OS X 10.13.6
Software rendering list URL	https://chromium.googlesource.com/chromium/src/+/4bbeebac88fdc09c97265e47c205868bbd190497/gpu/config/software_rendering_list.json
Driver bug list URL	https://chromium.googlesource.com/chromium/src/+/4bbeebac88fdc09c97265e47c205868bbd190497/gpu/config/gpu_driver_bug_list.json
ANGLE commit id	05c729f336ef
2D graphics backend	Skia/70 8adc53ec0ee4bbafbd9925024df38437c0fcf88a-
Command Line	/Applications/Google Chrome.app/Contents/MacOS/Google Chrome --flag-switches-begin --flag-switches-end
Driver Information
Initialization time	46
In-process GPU	false
Passthrough Command Decoder	false
Sandboxed	true
GPU0	VENDOR = 0x1002, DEVICE= 0x6821 *ACTIVE*
GPU1	VENDOR = 0x8086, DEVICE= 0x0d26
Optimus	false
AMD switchable	true
Driver vendor	ATI
Driver version	1.68.20
Driver date	
GPU CUDA compute capability major version	0
Pixel shader version	4.10
Vertex shader version	4.10
Max. MSAA samples	8
Machine model name	MacBookPro
Machine model version	11.5
GL_VENDOR	ATI Technologies Inc.
GL_RENDERER	AMD Radeon R9 M370X OpenGL Engine
GL_VERSION	4.1 ATI-1.68.20
GL_EXTENSIONS	GL_ARB_blend_func_extended GL_ARB_draw_buffers_blend GL_ARB_draw_indirect GL_ARB_ES2_compatibility GL_ARB_explicit_attrib_location GL_ARB_gpu_shader_fp64 GL_ARB_gpu_shader5 GL_ARB_instanced_arrays GL_ARB_internalformat_query GL_ARB_occlusion_query2 GL_ARB_sample_shading GL_ARB_sampler_objects GL_ARB_separate_shader_objects GL_ARB_shader_bit_encoding GL_ARB_shader_subroutine GL_ARB_shading_language_include GL_ARB_tessellation_shader GL_ARB_texture_buffer_object_rgb32 GL_ARB_texture_cube_map_array GL_ARB_texture_gather GL_ARB_texture_query_lod GL_ARB_texture_rgb10_a2ui GL_ARB_texture_storage GL_ARB_texture_swizzle GL_ARB_timer_query GL_ARB_transform_feedback2 GL_ARB_transform_feedback3 GL_ARB_vertex_attrib_64bit GL_ARB_vertex_type_2_10_10_10_rev GL_ARB_viewport_array GL_EXT_debug_label GL_EXT_debug_marker GL_EXT_depth_bounds_test GL_EXT_texture_compression_s3tc GL_EXT_texture_filter_anisotropic GL_EXT_texture_mirror_clamp GL_EXT_texture_sRGB_decode GL_APPLE_client_storage GL_APPLE_container_object_shareable GL_APPLE_flush_render GL_APPLE_object_purgeable GL_APPLE_rgb_422 GL_APPLE_row_bytes GL_APPLE_texture_range GL_ATI_texture_mirror_once GL_NV_texture_barrier
Disabled Extensions	GL_KHR_blend_equation_advanced GL_KHR_blend_equation_advanced_coherent
Disabled WebGL Extensions	
Window system binding vendor	
Window system binding version	
Window system binding extensions	
Direct rendering	Yes
Reset notification strategy	0x0000
GPU process crash count	0
Compositor Information
Tile Update Mode	Zero-copy
Partial Raster	Enabled
GpuMemoryBuffers Status
ATC	Software only
ATCIA	Software only
DXT1	Software only
DXT5	Software only
ETC1	Software only
R_8	GPU_READ, SCANOUT, SCANOUT_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE_PERSISTENT
R_16	Software only
RG_88	Software only
BGR_565	Software only
RGBA_4444	Software only
RGBX_8888	Software only
RGBA_8888	GPU_READ, SCANOUT, SCANOUT_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE_PERSISTENT
BGRX_8888	GPU_READ, SCANOUT, SCANOUT_CPU_READ_WRITE
BGRX_1010102	GPU_READ, SCANOUT, SCANOUT_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE_PERSISTENT
RGBX_1010102	Software only
BGRA_8888	GPU_READ, SCANOUT, SCANOUT_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE_PERSISTENT
RGBA_F16	GPU_READ, SCANOUT, SCANOUT_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE_PERSISTENT
YVU_420	Software only
YUV_420_BIPLANAR	GPU_READ, SCANOUT, SCANOUT_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE_PERSISTENT
UYVY_422	GPU_READ, SCANOUT, SCANOUT_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE, GPU_READ_CPU_READ_WRITE_PERSISTENT
Display(s) Information
Info	Display[69733314] bounds=[0,0 1440x900], workarea=[0,23 1440x821], scale=2, external.
Color space information	{primaries_d50_referred: [[0.6587, 0.3332], [0.3206, 0.6135], [0.1508, 0.0527]], transfer:0.0777*x + 0.0000 if x < 0.0450 else (0.9478*x + 0.0521)**2.4000 + -0.0000, matrix:RGB, range:FULL}
Bits per color component	8
Bits per pixel	24
Info	Display[724850450] bounds=[1440,-1096 2560x1440], workarea=[1440,-1073 2560x1417], scale=1, external.
Color space information	{primaries_d50_referred: [[0.6651, 0.3311], [0.3214, 0.6088], [0.1550, 0.0654]], transfer:0.0777*x + 0.0000 if x < 0.0450 else (0.9478*x + 0.0521)**2.4000 + -0.0000, matrix:RGB, range:FULL}
Bits per color component	8
Bits per pixel	24
Video Acceleration Information
Decode h264 baseline	up to 4096x2160 pixels
Decode h264 extended	up to 4096x2160 pixels
Decode h264 main	up to 4096x2160 pixels
Decode h264 high	up to 4096x2160 pixels
Encode h264 baseline	up to 4096x2160 pixels and/or 30.000 fps
Encode h264 main	up to 4096x2160 pixels and/or 30.000 fps
Encode h264 high	up to 4096x2160 pixels and/or 30.000 fps

Thank you for providing more feedback. Adding the requester to the cc list.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Re-tested this issue on Windows 10 and Mac OS 10.13.6 on the latest Stable 70.0.3538.102 and Canary 72.0.3610.0 and unable to reproduce the issue as mentioned in comment #2.
On navigating to the above given link, can observe that the image is rendering properly and the shadow is not clipped.

fserb@ Request you to check the chrome://gpu details provided in comment #7 and help in further triaging of the issue.

Thanks..

Please to reproduce run the script twice. The first time render ok.
Let me modify the scrip to render twice.

Il giorno gio 15 nov 2018 alle ore 09:49 susan.bo… via monorail <
monorail+v2.2788989951@chromium.org> ha scritto:

https://jsfiddle.net/hptkLs6d/3/

Please have a look with a redraw occured after the first one, the bug shows up  easier.

I can reproduce this on Mac Chrome 70.0.3538.102. See attached screenshot. The correct border shows up for a second, and then gets clipped. Note that it also gets clipped on the left. And by watching it, the shadow on the bottom also moves down a bit.

Deleted: Screen Shot 2018-11-15 at 11.45.07 AM.png 634 KB

	Screen Shot 2018-11-15 at 11.45.07 AM.png 634 KB View Download

Able to reproduce the issue on Windows 10, mac 10.13.6 and Ubuntu 17.10 using chrome reported version #70.0.3538.77 and latest canary #72.0.3611.0.

Bisect Information:
=====================
Good build: 61.0.3116.0
Bad Build : 61.0.3117.0

Change Log URL: 
https://chromium.googlesource.com/chromium/src/+log/f576d151955389c1b797409da6ed19c2a5530ff5..f8c414727d7e408eda97749c27598a714a17047a

From the above change log suspecting below change
Change-Id: Id600e9739bb97bf6766075ea2a987fd2039e53e5
Reviewed-on: https://skia-review.googlesource.com/18150

bsalomon@ - Could you please check whether this is caused with respect to your change, if not please help us in assigning it to the right owner.
ccing the reviewer of the issue as the author's chromium id seems to be inactive since 24 days ago.

Thanks...!!

I m the author of the issue and i m not inactive.

The following revision refers to this bug:
  https://skia.googlesource.com/skia/+/908bb23983d27ccd469c91556a313effe31c5052

commit 908bb23983d27ccd469c91556a313effe31c5052
Author: Brian Salomon <bsalomon@google.com>
Date: Mon Nov 19 15:35:42 2018

When outsetting for rect blur fast path use abs of scale factors.

Fixes an issue where negative scales caused an inset rather than an outset.

Add GM.

Bug:  chromium:899512 
Change-Id: I9164c76da479af80d4f5389b057ec52a946726fb
Reviewed-on: https://skia-review.googlesource.com/c/171641
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>

[add] https://crrev.com/908bb23983d27ccd469c91556a313effe31c5052/gm/crbug_899512.cpp
[modify] https://crrev.com/908bb23983d27ccd469c91556a313effe31c5052/src/core/SkBlurMF.cpp
[modify] https://crrev.com/908bb23983d27ccd469c91556a313effe31c5052/gn/gm.gni

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/19db32aa3860b32da80e36bc84bfd2ddf42a01b9

commit 19db32aa3860b32da80e36bc84bfd2ddf42a01b9
Author: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Date: Mon Nov 19 19:00:57 2018

Roll src/third_party/skia f7376330d11e..a1211832046d (8 commits)

https://skia.googlesource.com/skia.git/+log/f7376330d11e..a1211832046d


git log f7376330d11e..a1211832046d --date=short --no-merges --format='%ad %ae %s'
2018-11-19 halcanary@google.com SkPDF: move image serialization over to new immediate mode.
2018-11-19 mtklein@google.com clean up SkBitmapProcState a bit
2018-11-19 recipe-roller@chromium.org Roll recipe dependencies (trivial).
2018-11-19 bsalomon@google.com When outsetting for rect blur fast path use abs of scale factors.
2018-11-19 bsalomon@google.com Add single thread assertions to GrResourceCache functions called by GrGpuResource
2018-11-19 jvanverth@google.com Reland "Remove use of integers for atlas indexing"
2018-11-19 brianosman@google.com Use GrVertexWriter in GrDashOp
2018-11-19 recipe-roller@chromium.org Roll recipe dependencies (trivial).


Created with:
  gclient setdep -r src/third_party/skia@a1211832046d

The AutoRoll server is located here: https://autoroll.skia.org/r/skia-autoroll

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.

CQ_INCLUDE_TRYBOTS=luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux-chromeos-compile-dbg;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel;master.tryserver.blink:linux_trusty_blink_rel

BUG= chromium:899512 
TBR=csmartdalton@chromium.org

Change-Id: I076eaa7f924b584032ac32413163876a28cfb9ac
Reviewed-on: https://chromium-review.googlesource.com/c/1342009
Reviewed-by: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#609376}
[modify] https://crrev.com/19db32aa3860b32da80e36bc84bfd2ddf42a01b9/DEPS