Ganesh text rendering cleanup.

Rename GrTextStrike.{cpp.h} to GrFontCache.{cpp,h}
Move contents of GrTextStrike_impl.h to GrFontCache.h
Move glyph uploading to a separate function and remove harmful gotos
Add assert on glyph upload failure (shouldn't happen)

Review URL: https://codereview.chromium.org/780923002
diff --git a/src/gpu/GrBitmapTextContext.h b/src/gpu/GrBitmapTextContext.h
index a3d0eb2..747facf 100644
--- a/src/gpu/GrBitmapTextContext.h
+++ b/src/gpu/GrBitmapTextContext.h
@@ -48,6 +48,7 @@
 
     void init(const GrPaint&, const SkPaint&);
     void appendGlyph(GrGlyph::PackedID, SkFixed left, SkFixed top, GrFontScaler*);
+    bool uploadGlyph(GrGlyph*, GrFontScaler*);
     void flush();                 // automatically called by destructor
     void finish();
 };