Add a fast-path for independent inherited properties

third_party/WebKit/Source/core/css/CSSProperties.in

Index: third_party/WebKit/Source/core/css/CSSProperties.in
diff --git a/third_party/WebKit/Source/core/css/CSSProperties.in b/third_party/WebKit/Source/core/css/CSSProperties.in
index 593a53b3f1811d3d9556fdf22e24e919416bb739..2e1e7140afa391632a232b2f2b797a0453228996 100644
--- a/third_party/WebKit/Source/core/css/CSSProperties.in
+++ b/third_party/WebKit/Source/core/css/CSSProperties.in
@@ -45,6 +45,16 @@
 // The property will inherit by default if no value is specified, typically
 // mentioned in specifications as "Inherited: yes"
 
+// - independent
+// This property affects only one property on ComputedStyle, and can be
+// set directly during inheritance instead of forcing a recalc.
+// Recalcs only happen during a change propagation if at least one non-
+// independent property is changed.
+// Additionally, a change by an independent property must cause
+// ComputedStyle to change (e.g. font-size: 10px; and font-size: 1em;
+// result in the same ComputedStyle, but a change has still happened.
+// To make font-size independent, more information about the original
+// value needs to be stored).
 
 // The remaining arguments are used for the StyleBuilder and allow us to
 // succinctly describe how to apply properties. When default handlers are not
@@ -271,7 +281,7 @@ padding-top interpolable, initial=initialPadding, converter=convertLength
 paint-order inherited, svg, converter=convertPaintOrder
 perspective interpolable, converter=convertPerspective
 perspective-origin interpolable, converter=convertPosition
-pointer-events inherited
+pointer-events inherited, independent
 position custom_inherit
 quotes inherited, converter=convertQuotes
 resize custom_value
@@ -335,7 +345,7 @@ transition-timing-function custom_all
 unicode-bidi
 vector-effect svg
 vertical-align interpolable, custom_inherit, custom_value
-visibility interpolable, inherited
+visibility interpolable, inherited, independent
 x interpolable, svg, converter=convertLength
 y interpolable, svg, converter=convertLength
 -webkit-appearance type_name=ControlPart