Teach mapFill{X,Y}Position about initial values to individual background layers

Source/core/css/resolver/CSSToStyleMap.cpp

Index: Source/core/css/resolver/CSSToStyleMap.cpp
diff --git a/Source/core/css/resolver/CSSToStyleMap.cpp b/Source/core/css/resolver/CSSToStyleMap.cpp
index 276ced6386f87c2830361249f62b68d59affde1c..6aa5733c56e9f201ea22f7a09d3ca108c284dc03 100644
--- a/Source/core/css/resolver/CSSToStyleMap.cpp
+++ b/Source/core/css/resolver/CSSToStyleMap.cpp
@@ -218,6 +218,11 @@ void CSSToStyleMap::mapFillSize(CSSPropertyID, FillLayer* layer, CSSValue* value
 
 void CSSToStyleMap::mapFillXPosition(CSSPropertyID propertyID, FillLayer* layer, CSSValue* value) const
 {
+    if (value->isInitialValue()) {

[Julien - ping for review, 2014/01/10 13:37:03]

Shouldn't you also handle the keyword 'inherit' here too?

[davve, 2014/01/10 14:09:49]

Hm, I don't think so. The added code is for handling absent values in each
layer. You may not set 'inherit' in a way that may reach this code. All
'inherit' values should be handled further up in StyleBuilder::applyProperty,
unless I'm missing something.

+        layer->setXPosition(FillLayer::initialFillXPosition(layer->type()));
+        return;
+    }
+
     if (!value->isPrimitiveValue())
         return;
 
@@ -237,6 +242,11 @@ void CSSToStyleMap::mapFillXPosition(CSSPropertyID propertyID, FillLayer* layer,
 
 void CSSToStyleMap::mapFillYPosition(CSSPropertyID propertyID, FillLayer* layer, CSSValue* value) const
 {
+    if (value->isInitialValue()) {
+        layer->setYPosition(FillLayer::initialFillYPosition(layer->type()));
+        return;
+    }
+
     if (!value->isPrimitiveValue())
         return;