Work on getting things built with -Wimplicit-fallthrough. This CL was uploaded by git cl split.

Bug: 177475
R=xlai@chromium.org

Change-Id: Iaf7e65f74a55a20591ee49809210ef00548beb2d
Reviewed-on: https://chromium-review.googlesource.com/889784Reviewed-by: Olivia Lai <xlai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532874}

third_party/WebKit/Source/modules/canvas/canvas2d/CanvasRenderingContext2DState.cpp

@@ -560,8 +560,9 @@ const PaintFlags* CanvasRenderingContext2DState::GetFlags(
       break;
     default:
       NOTREACHED();
-    // no break on purpose: flags needs to be assigned to avoid compiler warning
-    // about uninitialized variable.
+      // no break on purpose: flags needs to be assigned to avoid compiler warning
+      // about uninitialized variable.
+      FALLTHROUGH;
     case kFillPaintType:
       UpdateFillStyle();
       flags = &fill_flags_;