This patch modifies RenderText so that it scans all of its characters up front to
determine whether or not the simple code path can be used for measurement/rendering
of the text for the whole run.
        
TextRun now has an additional field that indicates that the character scan is not
required, since the entire RenderText is known to be simple. This boolean is set
when constructing the TextRun from the places that make TextRuns from RenderTexts.
        
The character scan has been refactored into a static Font method so that it can be
called by RenderText. The scan of individual TextRuns is also done using the same method
so that the code is shared.

Reviewed by Dan Bernstein.

* platform/graphics/Font.cpp:
(WebCore::Font::codePath):
(WebCore::Font::characterRangeCodePath):
* platform/graphics/Font.h:
* platform/graphics/TextRun.h:
(WebCore::TextRun::TextRun):
(WebCore::TextRun::characterScanForCodePath):
(WebCore::TextRun::setCharacterScanForCodePath):
(TextRun):
* rendering/InlineTextBox.cpp:
(WebCore::InlineTextBox::constructTextRun):
* rendering/RenderBlockLineLayout.cpp:
(WebCore::textWidth):
* rendering/RenderText.cpp:
(WebCore::RenderText::RenderText):
(WebCore::RenderText::widthFromCache):
(WebCore::RenderText::setTextInternal):
(WebCore::RenderText::width):
(WebCore::RenderText::computeCanUseSimpleFontCodePath):
(WebCore):
* rendering/RenderText.h:
(RenderText):
(WebCore::RenderText::canUseSimpleFontCodePath):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@114032 268f45cc-cd09-0410-ab3c-d52691b4dbfc