Fix animations not starting on detached elements

Source/core/animation/EffectInput.cpp

Index: Source/core/animation/EffectInput.cpp
diff --git a/Source/core/animation/EffectInput.cpp b/Source/core/animation/EffectInput.cpp
index 82d9db38b47b621e9e29b2f877ea76411d219b3c..03f3893830b27631661f57df7f6db8e3b0ca1afc 100644
--- a/Source/core/animation/EffectInput.cpp
+++ b/Source/core/animation/EffectInput.cpp
@@ -199,9 +199,8 @@ PassRefPtrWillBeRawPtr<EffectModel> EffectInput::convert(Element* element, const
         return nullptr;
 
     // TODO(alancutter): Remove this once composited animations no longer depend on AnimatableValues.
-    if (!element->inActiveDocument())
-        return nullptr;

[shans, 2015/06/22 11:51:39]

doesn't this prevent elements that aren't in the document from being animated
using the API at all? That seems wrong.

[alancutter (OOO until 2018), 2015/06/23 03:47:04]

Correct, this patch fixes that.

-    element->document().updateLayoutTreeForNodeIfNeeded(element);
+    if (element->inActiveDocument())
+        element->document().updateLayoutTreeForNodeIfNeeded(element);
 
     StyleSheetContents* styleSheetContents = element->document().elementSheet().contents();
     StringKeyframeVector keyframes;