Fix the bug that negative outline-offset is covered up by composited

third_party/WebKit/Source/platform/graphics/CompositingReasons.h

Index: third_party/WebKit/Source/platform/graphics/CompositingReasons.h
diff --git a/third_party/WebKit/Source/platform/graphics/CompositingReasons.h b/third_party/WebKit/Source/platform/graphics/CompositingReasons.h
index 0513a7340904ea3c18e5d345c95d47a1bfab3bc3..e0d8667ac2a8733f308fcb0a47fc0aa770115095 100644
--- a/third_party/WebKit/Source/platform/graphics/CompositingReasons.h
+++ b/third_party/WebKit/Source/platform/graphics/CompositingReasons.h
@@ -86,12 +86,14 @@ const uint64_t CompositingReasonLayerForMask = UINT64_C(1) << 45;
 const uint64_t CompositingReasonLayerForClippingMask = UINT64_C(1) << 46;
 const uint64_t CompositingReasonLayerForScrollingBlockSelection = UINT64_C(1)
                                                                   << 47;
+// Composited layer painted on top of all other layers as decoration
+const uint64_t CompositingReasonLayerForDecoration = UINT64_C(1) << 48;
 
 // Composited elements with inline transforms trigger assumed overlap so that
 // we can update their transforms quickly.
-const uint64_t CompositingReasonInlineTransform = UINT64_C(1) << 48;
+const uint64_t CompositingReasonInlineTransform = UINT64_C(1) << 49;
 
-const uint64_t CompositingReasonCompositorProxy = UINT64_C(1) << 49;
+const uint64_t CompositingReasonCompositorProxy = UINT64_C(1) << 50;
 
 // Various combinations of compositing reasons are defined here also, for more
 // intutive and faster bitwise logic.