compile confirm no-op failing on chromium.win/Win x64 Builder

Failure logs:
ninja explain: output obj/third_party/WebKit/Source/core/css/css_6/CSSPropertyAPIFontStyle.obj older than most recent input gen/blink/core/css/properties/CSSPropertyAPIFontStyle.h (527479194 vs 527480822)
ninja explain: obj/third_party/WebKit/Source/core/css/css_6/CSSPropertyAPIFontStyle.obj is dirty


Builders failed on: 
- Win x64 Builder:   https://build.chromium.org/p/chromium.win/builders/Win%20x64%20Builder
- 

First failure:
https://uberchromegw.corp.google.com/i/chromium.win/builders/Win%20x64%20Builder/builds/37776

This seems to be related to:
https://chromium-review.googlesource.com/666363

which changes some build script related to CSSPropertyAP

bugsnash@chromium.org, can you take a look?