Handle null baseStyle in getPropertiesNotIn

Source/core/editing/EditingStyle.cpp

 /*
  * Copyright (C) 2007, 2008, 2009 Apple Computer, Inc.
  * Copyright (C) 2010, 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 1410 matching lines @@
     , m_applyItalic(false)
     , m_applyUnderline(false)
     , m_applyLineThrough(false)
     , m_applySubscript(false)
     , m_applySuperscript(false)
 {
     Document* document = position.document();
     if (!style || !style->style() || !document || !document->frame())
         return;
 
     RefPtrWillBeRawPtr<CSSComputedStyleDeclaration> computedStyle = position.computedStyle();

[yosin_UTC9, 2015/03/10 05:27:07]

Where |position| does point? Does |point| point to |Document|?
Since |Position::computedStyle()| returns computed style of element, it should
not be null.
Call sites, in this case |ApplyStyleCommand::applyBlockStyle|, should not try to
extract style for |Position| which doesn't have style.

[rwlbuis, 2015/03/10 23:44:21]

Indeed position is a Document in the case where computedStyle returns null.

     // FIXME: take care of background-color in effect
     RefPtrWillBeRawPtr<MutableStylePropertySet> mutableStyle = getPropertiesNotIn(style->style(), computedStyle.get());
 
     reconcileTextDecorationProperties(mutableStyle.get());
     if (!document->frame()->editor().shouldStyleWithCSS())
-        extractTextStyles(document, mutableStyle.get(), computedStyle->fixedPitchFontType());
+        extractTextStyles(document, mutableStyle.get(), computedStyle ? computedStyle->fixedPitchFontType() : NonFixedPitchFont);
 
     // Changing the whitespace style in a tab span would collapse the tab into a space.
     if (isTabHTMLSpanElementTextNode(position.deprecatedNode()) || isTabHTMLSpanElement((position.deprecatedNode())))
         mutableStyle->removeProperty(CSSPropertyWhiteSpace);
 
     // If unicode-bidi is present in mutableStyle and direction is not, then add direction to mutableStyle.
     // FIXME: Shouldn't this be done in getPropertiesNotIn?
     if (mutableStyle->getPropertyCSSValue(CSSPropertyUnicodeBidi) && !style->style()->getPropertyCSSValue(CSSPropertyDirection))
         mutableStyle->setProperty(CSSPropertyDirection, style->style()->getPropertyValue(CSSPropertyDirection));
 
@@ skipping 123 matching lines @@
     if (!fontWeight->isPrimitiveValue())
         return true;
 
     CSSValueID value = toCSSPrimitiveValue(fontWeight)->getValueID();
     return value == CSSValueLighter || value == CSSValueBolder;
 }
 
 PassRefPtrWillBeRawPtr<MutableStylePropertySet> getPropertiesNotIn(StylePropertySet* styleWithRedundantProperties, CSSStyleDeclaration* baseStyle)
 {
     ASSERT(styleWithRedundantProperties);
-    ASSERT(baseStyle);
     RefPtrWillBeRawPtr<MutableStylePropertySet> result = styleWithRedundantProperties->mutableCopy();
+    if (!baseStyle)
+        return result.release();
 
     result->removeEquivalentProperties(baseStyle);
 
     RefPtrWillBeRawPtr<CSSValue> baseTextDecorationsInEffect = baseStyle->getPropertyCSSValueInternal(CSSPropertyWebkitTextDecorationsInEffect);
     diffTextDecorations(result.get(), textDecorationPropertyForEditing(), baseTextDecorationsInEffect.get());
     diffTextDecorations(result.get(), CSSPropertyWebkitTextDecorationsInEffect, baseTextDecorationsInEffect.get());
 
     if (RefPtrWillBeRawPtr<CSSValue> baseFontWeight = baseStyle->getPropertyCSSValueInternal(CSSPropertyFontWeight)) {
         if (RefPtrWillBeRawPtr<CSSValue> fontWeight = result->getPropertyCSSValue(CSSPropertyFontWeight)) {
             if (!fontWeightNeedsResolving(fontWeight.get()) && (fontWeightIsBold(fontWeight.get()) == fontWeightIsBold(baseFontWeight.get())))
@@ skipping 85 matching lines @@
 {
     for (Node* ancestor = node; ancestor; ancestor = ancestor->parentNode()) {
         RefPtrWillBeRawPtr<CSSComputedStyleDeclaration> ancestorStyle = CSSComputedStyleDeclaration::create(ancestor);
         if (!hasTransparentBackgroundColor(ancestorStyle.get()))
             return ancestorStyle->getPropertyCSSValue(CSSPropertyBackgroundColor);
     }
     return nullptr;
 }
 
 }