Support getComputedStyle for non-rendered pseudo elements.

Source/core/css/resolver/StyleResolver.cpp

Index: Source/core/css/resolver/StyleResolver.cpp
diff --git a/Source/core/css/resolver/StyleResolver.cpp b/Source/core/css/resolver/StyleResolver.cpp
index 747a305c5b1aa2cb547204d094778e647ecce4f0..f8e1636e85a58dc73d72be958296e2cc77d336b7 100644
--- a/Source/core/css/resolver/StyleResolver.cpp
+++ b/Source/core/css/resolver/StyleResolver.cpp
@@ -776,6 +776,7 @@ bool StyleResolver::pseudoStyleForElementInternal(Element& element, const Pseudo
         state.setParentStyle(RenderStyle::clone(state.style()));
     }
 
+    state.style()->setStyleType(pseudoStyleRequest.pseudoId);
     state.fontBuilder().initForStyleResolve(state.document(), state.style());
 
     // Since we don't use pseudo-elements in any of our quirk/print
@@ -792,8 +793,6 @@ bool StyleResolver::pseudoStyleForElementInternal(Element& element, const Pseudo
         if (collector.matchedResult().matchedProperties.isEmpty())
             return false;
 
-        state.style()->setStyleType(pseudoStyleRequest.pseudoId);
-
         applyMatchedProperties(state, collector.matchedResult());
         applyCallbackSelectors(state);
 
@@ -828,8 +827,11 @@ PassRefPtr<RenderStyle> StyleResolver::pseudoStyleForElement(Element* element, c
         return nullptr;
 
     StyleResolverState state(document(), element, parentStyle);
-    if (!pseudoStyleForElementInternal(*element, pseudoStyleRequest, parentStyle, state))
-        return nullptr;
+    if (!pseudoStyleForElementInternal(*element, pseudoStyleRequest, parentStyle, state)) {
+        if (pseudoStyleRequest.type == PseudoStyleRequest::ForRenderer)

[esprehn, 2014/09/17 19:04:42]

This doesn't make sense, pseudoStyleForElementInternal only returns false if
there's no matched properties. If there's no matched properties then you're just
returning the default UA style here. I don't think you're returning the correct
style...

[rune, 2014/09/17 20:00:33]

http://www.w3.org/TR/CSS2/generate.html#before-after-content:

"The :before and :after pseudo-elements inherit any inheritable properties from
the element in the document tree to which they are attached."
"In a :before or :after pseudo-element declaration, non-inherited properties
take their initial values."

That is exactly what happens in:

https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...

+            return nullptr;
+        return state.takeStyle();
+    }
 
     if (PseudoElement* pseudoElement = element->pseudoElement(pseudoStyleRequest.pseudoId))
         setAnimationUpdateIfNeeded(state, *pseudoElement);