Clear mutable inline style when it is empty.

Source/core/dom/Element.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Peter Kelly (pmk@post.com)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012, 2013 Apple Inc. All rights reserved.
  *           (C) 2007 Eric Seidel (eric@webkit.org)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 3414 matching lines @@
 {
     ensureElementRareData().setHasPendingResources(false);
 }
 
 void Element::synchronizeStyleAttributeInternal() const
 {
     ASSERT(isStyledElement());
     ASSERT(elementData());
     ASSERT(elementData()->m_styleAttributeIsDirty);
     elementData()->m_styleAttributeIsDirty = false;
-    if (const StylePropertySet* inlineStyle = this->inlineStyle())
-        const_cast<Element*>(this)->setSynchronizedLazyAttribute(styleAttr, inlineStyle->asText());
+    const StylePropertySet* inlineStyle = this->inlineStyle();
+    const_cast<Element*>(this)->setSynchronizedLazyAttribute(styleAttr,
+        inlineStyle ? AtomicString(inlineStyle->asText()) : nullAtom);
 }
 
 CSSStyleDeclaration* Element::style()
 {
     if (!isStyledElement())
         return 0;
     return ensureElementRareData().ensureInlineCSSStyleDeclaration(this);
 }
 
 MutableStylePropertySet* Element::ensureMutableInlineStyle()
 {
     ASSERT(isStyledElement());
     RefPtr<StylePropertySet>& inlineStyle = ensureUniqueElementData()->m_inlineStyle;
     if (!inlineStyle) {
         CSSParserMode mode = (!isHTMLElement() || document().inQuirksMode()) ? HTMLQuirksMode : HTMLStandardMode;
         inlineStyle = MutableStylePropertySet::create(mode);
     } else if (!inlineStyle->isMutable()) {
         inlineStyle = inlineStyle->mutableCopy();
     }
     return toMutableStylePropertySet(inlineStyle);
 }
 
+void Element::clearMutableInlineStyleIfEmpty()
+{
+    if (ensureMutableInlineStyle()->isEmpty()) {
+        ensureUniqueElementData()->m_inlineStyle.clear();
+    }
+}
+
 PropertySetCSSStyleDeclaration* Element::inlineStyleCSSOMWrapper()
 {
     if (!inlineStyle() || !inlineStyle()->hasCSSOMWrapper())
         return 0;
     PropertySetCSSStyleDeclaration* cssomWrapper = ensureMutableInlineStyle()->cssStyleDeclaration();
     ASSERT(cssomWrapper && cssomWrapper->parentElement() == this);
     return cssomWrapper;
 }
 
 inline void Element::setInlineStyleFromString(const AtomicString& newStyleString)
@@ skipping 88 matching lines @@
         return false;
     bool changes = ensureMutableInlineStyle()->removeProperty(propertyID);
     if (changes)
         inlineStyleChanged();
     return changes;
 }
 
 void Element::removeAllInlineStyleProperties()
 {
     ASSERT(isStyledElement());
-    if (!inlineStyle() || inlineStyle()->isEmpty())
+    if (!inlineStyle())
         return;
     ensureMutableInlineStyle()->clear();
     inlineStyleChanged();
 }
 
 void Element::addSubresourceAttributeURLs(ListHashSet<KURL>& urls) const
 {
     ASSERT(isStyledElement());
     if (const StylePropertySet* inlineStyle = elementData() ? elementData()->inlineStyle() : 0)
         inlineStyle->addSubresourceStyleURLs(urls, document().elementSheet()->contents());
@@ skipping 71 matching lines @@
     // Before doing so, we need to resolve issues in HTMLSelectElement::recalcListItems
     // and RenderMenuList::setText. See also https://bugs.webkit.org/show_bug.cgi?id=88405
     if (hasTagName(optionTag) || hasTagName(optgroupTag))
         return false;
     if (FullscreenElementStack::isActiveFullScreenElement(this))
         return false;
     return true;
 }
 
 } // namespace WebCore