Clear need for animation style for forced styleForElement.

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index 832ecfb63e36606175e5ee0e403dc324cae2608a..dfea11b9ec9cd519a3a934e2cabed905271c846f 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -1600,18 +1600,26 @@ void Document::inheritHtmlAndBodyElementStyles(StyleRecalcChange change)
     ASSERT(inStyleRecalc());
     ASSERT(documentElement());
 
+    bool didRecalcDocumentElement = false;
     RefPtr<LayoutStyle> documentElementStyle = documentElement()->layoutStyle();
-    if (!documentElementStyle || documentElement()->needsStyleRecalc() || change == Force)
+    if (change == Force)
+        documentElement()->clearAnimationStyleChange();
+    if (!documentElementStyle || documentElement()->needsStyleRecalc() || change == Force) {
         documentElementStyle = ensureStyleResolver().styleForElement(documentElement());
+        didRecalcDocumentElement = true;
+    }
 
     WritingMode rootWritingMode = documentElementStyle->writingMode();
     TextDirection rootDirection = documentElementStyle->direction();
 
     HTMLElement* body = this->body();
     RefPtr<LayoutStyle> bodyStyle;
+
     if (body) {
         bodyStyle = body->layoutStyle();
-        if (!bodyStyle || body->needsStyleRecalc() || documentElement()->needsStyleRecalc() || change == Force)
+        if (didRecalcDocumentElement)
+            body->clearAnimationStyleChange();
+        if (!bodyStyle || body->needsStyleRecalc() || didRecalcDocumentElement)
             bodyStyle = ensureStyleResolver().styleForElement(body, documentElementStyle.get());
         rootWritingMode = bodyStyle->writingMode();
         rootDirection = bodyStyle->direction();