Fix   fallback glyph lookup

Source/platform/fonts/Font.cpp

Index: Source/platform/fonts/Font.cpp
diff --git a/Source/platform/fonts/Font.cpp b/Source/platform/fonts/Font.cpp
index a45007103723194869d91cbda93eb767f5ed9d96..025dd90206c71081e9d7f04ae070a068cd41bf33 100644
--- a/Source/platform/fonts/Font.cpp
+++ b/Source/platform/fonts/Font.cpp
@@ -525,13 +525,13 @@ GlyphData Font::glyphDataForCharacter(UChar32& c, bool mirror, bool normalizeSpa
         if (characterFontData) {
             // Got the fallback glyph and font.
             GlyphPage* fallbackPage = GlyphPageTreeNode::getRootChild(characterFontData.get(), pageNumber)->page();
-            GlyphData data = fallbackPage && fallbackPage->glyphForCharacter(c) ? fallbackPage->glyphDataForCharacter(c) : characterFontData->missingGlyphData();
+            GlyphData data = fallbackPage && fallbackPage->glyphForCharacter(characterToRender) ? fallbackPage->glyphDataForCharacter(characterToRender) : characterFontData->missingGlyphData();

[kochi, 2015/08/26 12:02:59]

On this line, fallbackPage->glyphForCharacter(0xa0) fails as the font does not
have the glyph for it, so it falls back to characterFontData->missingGlyphData()
path.

[kojii, 2015/08/26 13:45:09]

Yeah, this code path looks ok, so the caller should get missingGlyphData, which
is glyph == 0.

When Font returns glyph == 0, why Linux does not render the glyph while Android
renders it is still a mystery.

What are the CSS in the reproducing pages? Do they specify the font family,
'serif', or nothing?

[kochi, 2015/08/26 16:06:07]

I think on Linux fallbackPage->glyphForCharacter(c) succeeds, and
missingGlyphData() is never
called (of course, it depends on the fontconfig settings, though).

On Android (JA locale), fallbackPage also contains MotoyaLMaru and if it's given
0xa0, lookup
fails again (this is hypothesis, needs verification).

             // Cache it so we don't have to do system fallback again next time.
             if (variant == NormalVariant) {
-                page->setGlyphDataForCharacter(c, data.glyph, data.fontData);
+                page->setGlyphDataForCharacter(characterToRender, data.glyph, data.fontData);
                 data.fontData->setMaxGlyphPageTreeLevel(std::max(data.fontData->maxGlyphPageTreeLevel(), node->level()));
-                if (data.fontData->platformData().isVerticalAnyUpright() && !data.fontData->isTextOrientationFallback() && !Character::isCJKIdeographOrSymbol(c))
-                    return glyphDataForNonCJKCharacterWithGlyphOrientation(c, m_fontDescription.isVerticalUpright(c), data, pageNumber);
+                if (data.fontData->platformData().isVerticalAnyUpright() && !data.fontData->isTextOrientationFallback() && !Character::isCJKIdeographOrSymbol(characterToRender))
+                    return glyphDataForNonCJKCharacterWithGlyphOrientation(characterToRender, m_fontDescription.isVerticalUpright(characterToRender), data, pageNumber);
             }
             return data;
         }