Add m_isGlyphLookupMode to UniscribeHelper class and set it to true when fill...

third_party/WebKit/WebCore/platform/graphics/chromium/UniscribeHelper.cpp

Index: third_party/WebKit/WebCore/platform/graphics/chromium/UniscribeHelper.cpp
===================================================================
--- third_party/WebKit/WebCore/platform/graphics/chromium/UniscribeHelper.cpp	(revision 7936)
+++ third_party/WebKit/WebCore/platform/graphics/chromium/UniscribeHelper.cpp	(working copy)
@@ -86,6 +86,8 @@
     , m_spaceWidth(0)
     , m_wordSpacing(0)
     , m_ascent(0)
+    , m_disableFontFallback(false)
+
 {
     m_logfont.lfFaceName[0] = 0;
 }
@@ -508,7 +510,10 @@
     HDC tempDC = NULL;
     HGDIOBJ oldFont = 0;
     HRESULT hr;
-    bool lastFallbackTried = false;
+    // When used to fill up glyph pages for simple scripts in non-BMP,
+    // we don't want any font fallback in this class. The simple script
+    // font path can take care of font fallback.
+    bool lastFallbackTried = m_disableFontFallback;
     bool result;
 
     int generatedGlyphs = 0;
@@ -572,7 +577,8 @@
             tempDC = NULL;
         }
 
-        if (NextWinFontData(&hfont, &scriptCache, &fontProperties, &ascent)) {
+        if (!m_disableFontFallback &&
+            NextWinFontData(&hfont, &scriptCache, &fontProperties, &ascent)) {
             // The primary font does not support this run. Try next font.
             // In case of web page rendering, they come from fonts specified in
             // CSS stylesheets.
@@ -688,6 +694,13 @@
                    shaping))
             continue;
 
+        // At the moment, the only time m_disableFontFallback is set is
+        // when we look up glyph indices for non-BMP code ranges. So,
+        // we can skip the glyph placement. When that becomes not the case
+        // any more, we have to add a new flag to control glyph placement.
+        if (m_disableFontFallback)
+          continue;
+
         // Compute placements. Note that offsets is documented incorrectly
         // and is actually an array.