Avoid re-parsing of string in fillText and measureText in Canvas

Source/platform/fonts/Font.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2006, 2010, 2011 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 409 matching lines @@
             if (data.glyph != verticalRightData.glyph)
                 return std::make_pair(data, page);
             // The glyphs are identical, meaning that we should just use the horizontal glyph.
             if (verticalRightData.fontData)
                 return std::make_pair(verticalRightData, verticalRightPage);
         }
     }
     return std::make_pair(data, page);
 }
 
-std::pair<GlyphData, GlyphPage*> Font::glyphDataAndPageForCharacter(UChar32 c, bool mirror, FontDataVariant variant) const
+std::pair<GlyphData, GlyphPage*> Font::glyphDataAndPageForCharacter(UChar32& c, bool mirror, bool normalizeSpace, FontDataVariant variant) const
 {
     ASSERT(isMainThread());
 
     if (variant == AutoVariant) {
         if (m_fontDescription.variant() == FontVariantSmallCaps && !primaryFont()->isSVGFont()) {
             UChar32 upperC = toUpper(c);
             if (upperC != c) {
                 c = upperC;
                 variant = SmallCapsVariant;
             } else {
                 variant = NormalVariant;
             }
         } else {
             variant = NormalVariant;
         }
     }
 
+    if (normalizeSpace && Character::isNormalizedCanvasSpaceCharacter(c))
+        c = space;
+
     if (mirror)
         c = mirroredChar(c);
 
     unsigned pageNumber = (c / GlyphPage::size);
 
     GlyphPageTreeNode* node = m_fontFallbackList->getPageNode(pageNumber);
     if (!node) {
         node = GlyphPageTreeNode::getRootChild(fontDataAt(0), pageNumber);
         m_fontFallbackList->setPageNode(pageNumber, node);
     }
@@ skipping 137 matching lines @@
         if (mark.length() < 2)
             return false;
 
         UChar low = mark[1];
         if (!U16_IS_TRAIL(low))
             return false;
 
         character = U16_GET_SUPPLEMENTARY(character, low);
     }
 
-    glyphData = glyphDataForCharacter(character, false, EmphasisMarkVariant);
+    bool normalizeSpace = false;
+    glyphData = glyphDataForCharacter(character, false, normalizeSpace, EmphasisMarkVariant);
     return true;
 }
 
 int Font::emphasisMarkAscent(const AtomicString& mark) const
 {
     FontCachePurgePreventer purgePreventer;
 
     GlyphData markGlyphData;
     if (!getEmphasisMarkGlyphData(mark, markGlyphData))
         return 0;
@@ skipping 276 matching lines @@
                 if (delta <= 0)
                     break;
             }
         }
     }
 
     return offset;
 }
 
 } // namespace blink