This is a very minor feature. Not sure it warrants going through the formal launch process.

@chrishtr: WDYT?

I think this should go through an intent, even though it's small. It's
important for visibility and documentation of changes, for the benefit of not
just us but the community of developers.

@fserb:
The launch process is this: https://www.chromium.org/blink/launching-features

Also, you will need to discover the magic of our bindings code generator: https://www.chromium.org/blink/webidl

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/11a275c5522ae4dbf8e3dee5c7246e74141b5142

commit 11a275c5522ae4dbf8e3dee5c7246e74141b5142
Author: fserb <fserb@chromium.org>
Date: Fri Mar 24 00:04:09 2017

Adds SVGImageElement to CanvasImageSource

Relevant spec: https://html.spec.whatwg.org/multipage/scripting.html#image-sources-for-2d-rendering-contexts:htmlorsvgimageelement

SVGImageElement should be part of CanvasImageSource union typedef, i.e., be allowed as an source for drawImage(). This CL does that, while creating a common interface for both HTMLImageElement and SVGImageElement.

BUG= 695662 

Review-Url: https://codereview.chromium.org/2723093004
Cr-Commit-Position: refs/heads/master@{#459289}

[modify] https://crrev.com/11a275c5522ae4dbf8e3dee5c7246e74141b5142/third_party/WebKit/LayoutTests/canvas/philip/tests/2d.pattern.image.string-expected.txt
[modify] https://crrev.com/11a275c5522ae4dbf8e3dee5c7246e74141b5142/third_party/WebKit/LayoutTests/canvas/philip/tests/2d.pattern.image.undefined-expected.txt
[add] https://crrev.com/11a275c5522ae4dbf8e3dee5c7246e74141b5142/third_party/WebKit/LayoutTests/fast/canvas/canvas-drawImage-svg-expected.html
[add] https://crrev.com/11a275c5522ae4dbf8e3dee5c7246e74141b5142/third_party/WebKit/LayoutTests/fast/canvas/canvas-drawImage-svg.html
[add] https://crrev.com/11a275c5522ae4dbf8e3dee5c7246e74141b5142/third_party/WebKit/LayoutTests/fast/canvas/resources/rect.svg
[add] https://crrev.com/11a275c5522ae4dbf8e3dee5c7246e74141b5142/third_party/WebKit/LayoutTests/http/tests/security/canvas-remote-read-remote-svg-image.html
[modify] https://crrev.com/11a275c5522ae4dbf8e3dee5c7246e74141b5142/third_party/WebKit/Source/bindings/modules/v8/generated.gni
[modify] https://crrev.com/11a275c5522ae4dbf8e3dee5c7246e74141b5142/third_party/WebKit/Source/core/html/BUILD.gn
[modify] https://crrev.com/11a275c5522ae4dbf8e3dee5c7246e74141b5142/third_party/WebKit/Source/core/html/HTMLImageElement.cpp
[modify] https://crrev.com/11a275c5522ae4dbf8e3dee5c7246e74141b5142/third_party/WebKit/Source/core/html/HTMLImageElement.h
[add] https://crrev.com/11a275c5522ae4dbf8e3dee5c7246e74141b5142/third_party/WebKit/Source/core/html/canvas/CanvasImageElementSource.cpp
[add] https://crrev.com/11a275c5522ae4dbf8e3dee5c7246e74141b5142/third_party/WebKit/Source/core/html/canvas/CanvasImageElementSource.h
[modify] https://crrev.com/11a275c5522ae4dbf8e3dee5c7246e74141b5142/third_party/WebKit/Source/core/html/canvas/CanvasImageSource.h
[modify] https://crrev.com/11a275c5522ae4dbf8e3dee5c7246e74141b5142/third_party/WebKit/Source/core/svg/SVGImageElement.cpp
[modify] https://crrev.com/11a275c5522ae4dbf8e3dee5c7246e74141b5142/third_party/WebKit/Source/core/svg/SVGImageElement.h
[modify] https://crrev.com/11a275c5522ae4dbf8e3dee5c7246e74141b5142/third_party/WebKit/Source/modules/canvas2d/BaseRenderingContext2D.cpp
[modify] https://crrev.com/11a275c5522ae4dbf8e3dee5c7246e74141b5142/third_party/WebKit/Source/modules/canvas2d/BaseRenderingContext2D.h
[modify] https://crrev.com/11a275c5522ae4dbf8e3dee5c7246e74141b5142/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.h
[modify] https://crrev.com/11a275c5522ae4dbf8e3dee5c7246e74141b5142/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.idl

This is done. Moving forward to ImageBitmapSource now.