Ignore inherit fonts on OffscreenCanvas2D

Bug: 782119
Change-Id: I534996d8f222b0ed277de74c0ee6f860f7d60a36
Reviewed-on: https://chromium-review.googlesource.com/759093Reviewed-by: Justin Novosad <junov@chromium.org>
Commit-Queue: Fernando Serboncini <fserb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#515250}

third_party/WebKit/Source/modules/canvas/offscreencanvas2d/OffscreenCanvasRenderingContext2D.cpp

@@ -286,6 +286,11 @@ void OffscreenCanvasRenderingContext2D::setFont(const String& new_font) {
       MutableStylePropertySet::Create(kHTMLStandardMode);
   if (!style)
     return;
+
+  if (EqualIgnoringASCIICase(new_font, "inherit")) {
+    return;
+  }
+
   CSSParser::ParseValue(style, CSSPropertyFont, new_font, true);
 
   FontDescription desc =