Moving GraphicsContext and dependencies from core to platform.

Source/platform/fonts/GlyphPage.h

Index: Source/platform/fonts/GlyphPage.h
diff --git a/Source/platform/fonts/GlyphPage.h b/Source/platform/fonts/GlyphPage.h
index 93b99bd7c4ae42d998ec0048e47668d1431af1f1..98812862bef202ef52c385d08af2e62e96294793 100644
--- a/Source/platform/fonts/GlyphPage.h
+++ b/Source/platform/fonts/GlyphPage.h
@@ -30,6 +30,7 @@
 #ifndef GlyphPage_h
 #define GlyphPage_h
 
+#include "platform/PlatformExport.h"
 #include "platform/fonts/Glyph.h"
 #include <string.h>
 #include "wtf/PassRefPtr.h"
@@ -67,7 +68,7 @@ struct GlyphData {
 // missing in the primary font. It is owned by exactly one GlyphPageTreeNode,
 // although multiple nodes may reference it as their "page" if they are supposed
 // to be overriding the parent's node, but provide no additional information.
-class GlyphPage : public RefCounted<GlyphPage> {
+class PLATFORM_EXPORT GlyphPage : public RefCounted<GlyphPage> {
 public:
     static PassRefPtr<GlyphPage> createForMixedFontData(GlyphPageTreeNode* owner)
     {