Link to Builder:
================
https://uberchromegw.corp.google.com/i/official.desktop/builders/win-clang/builds/185
https://uberchromegw.corp.google.com/i/official.desktop/builders/win64-clang/builds/186

Link to Log File:
=================
https://uberchromegw.corp.google.com/i/official.desktop/builders/win-clang/builds/185/steps/compile/logs/stdio
https://uberchromegw.corp.google.com/i/official.desktop/builders/win64-clang/builds/186/steps/compile/logs/stdio

Error from the Log:
===================
FAILED: obj/third_party/WebKit/Source/bindings/core/v8/bindings_core_impl/RadioNodeListOrElement.obj 
../../third_party/llvm-build/Release+Asserts/bin/clang-cl.exe /nologo /showIncludes /FC @obj/third_party/WebKit/Source/bindings/core/v8/bindings_core_impl/RadioNodeListOrElement.obj.rsp /c gen/blink/bindings/core/v8/RadioNodeListOrElement.cpp /Foobj/third_party/WebKit/Source/bindings/core/v8/bindings_core_impl/RadioNodeListOrElement.obj /Fd"obj/third_party/WebKit/Source/bindings/core/v8/bindings_core_impl_cc.pdb"
In file included from gen/blink/bindings/core/v8/RadioNodeListOrElement.cpp:18:
In file included from ../../third_party/WebKit/Source\core/animation/ElementAnimation.h:38:
In file included from ../../third_party/WebKit/Source\core/animation/ElementAnimations.h:36:
In file included from ../../third_party/WebKit/Source\core/animation/css/CSSAnimations.h:40:
In file included from ../../third_party/WebKit/Source\core/css/resolver/StyleResolverState.h:37:
In file included from ../../third_party/WebKit/Source\core/style/CachedUAStyle.h:26:
In file included from ../../third_party/WebKit/Source\core/style/ComputedStyle.h:48:
In file included from ../../third_party/WebKit/Source\core/style/StyleInheritedData.h:30:
In file included from ../../third_party/WebKit/Source\platform/fonts/Font.h:31:
In file included from ../../third_party/WebKit/Source\platform/fonts/FontFallbackList.h:26:
In file included from ../../third_party/WebKit/Source\platform/fonts/FontSelector.h:31:
C:\b\build\slave\win-clang\build\src\third_party\WebKit\Source\platform\fonts\SegmentedFontData.h(66,1):  error: implicit conversion from 'int' to 'unsigned char' changes value from 256 to 0 [-Werror,-Wconstant-conversion]
DEFINE_FONT_DATA_TYPE_CASTS(SegmentedFontData, true);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
C:\b\build\slave\win-clang\build\src\third_party\WebKit\Source\platform\fonts\FontData.h(64,3):  note: expanded from macro 'DEFINE_FONT_DATA_TYPE_CASTS'
  DEFINE_TYPE_CASTS(thisType, FontData, fontData,            \
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
C:\b\build\slave\win-clang\build\src\third_party\WebKit\Source\wtf\Assertions.h(248,5):  note: expanded from macro 'DEFINE_TYPE_CASTS'
    CHECK(referencePredicate);                                                \
    ^~~~~~~~~~~~~~~~~~~~~~~~~
C:\b\build\slave\win-clang\build\src\base\logging.h(540,28):  note: expanded from macro 'CHECK'
  UNLIKELY(!(condition)) ? IMMEDIATE_CRASH() : EAT_STREAM_PARAMETERS
                           ^~~~~~~~~~~~~~~~~
C:\b\build\slave\win-clang\build\src\base\logging.h(515,59):  note: expanded from macro 'IMMEDIATE_CRASH'
   (void)(*reinterpret_cast<volatile unsigned char*>(0) = __COUNTER__))
                                                        ~ ^~~~~~~~~~~

Change Log: https://chromium.googlesource.com/chromium/src/+log/58.0.3018.0..58.0.3019.2?pretty=fuller&n=10000

Suspecting below change could be a possible root cause:

https://chromium.googlesource.com/chromium/src/+/92bbdc39154ce7cbbc939d9a4c5ee371691ab811

@ scottmg: request you to please take a look into it. Please help us to find an owner if not with respect to your change.

Thanks.!