Make EditingStyle to use VisibleSelection::toNormalizedEphemeralRange()...

Make EditingStyle to use VisibleSelection::toNormalizedEphemeralRange() instead of toNormalizedRange()

This patch changes |EditingStyle| class to use |toNormalizedEphemeralRange()|
in |VisibleSelection| class instead of |toNormalizedRange()| as a preparation
of templatizing |VisibleSelection| to use templatized positions instead of
DOM position to represent range and avoid registering temporary |Range|
object into |Document|.

This patch is a preparation of making selection to handle granularity for web
component, http://crrev.com/1277863002

BUG=388681, 513568
TEST=n/a; no behavior changes

Review URL: https://codereview.chromium.org/1314713004

git-svn-id: svn://svn.chromium.org/blink/trunk@201112 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/editing/EditingStyle.cpp

@@ -1338,8 +1338,8 @@ PassRefPtrWillBeRawPtr<EditingStyle> EditingStyle::styleAtSelectionStart(const V
     // Also, if the selection is a range, ignore the background color at the start of selection,
     // and find the background color of the common ancestor.
     if (shouldUseBackgroundColorInEffect && (selection.isRange() || hasTransparentBackgroundColor(style->m_mutableStyle.get()))) {
-        RefPtrWillBeRawPtr<Range> range(selection.toNormalizedRange());
-        if (PassRefPtrWillBeRawPtr<CSSValue> value = backgroundColorInEffect(range->commonAncestorContainer()))
+        const EphemeralRange range(selection.toNormalizedEphemeralRange());
+        if (PassRefPtrWillBeRawPtr<CSSValue> value = backgroundColorInEffect(Range::commonAncestorContainer(range.startPosition().computeContainerNode(), range.endPosition().computeContainerNode())))
             style->setProperty(CSSPropertyBackgroundColor, value->cssText());
     }