remove old text contexts and fontcache

BUG=skia:

Review URL: https://codereview.chromium.org/1104343003
diff --git a/src/gpu/SkGpuDevice.cpp b/src/gpu/SkGpuDevice.cpp
index 337f400..0decb32 100644
--- a/src/gpu/SkGpuDevice.cpp
+++ b/src/gpu/SkGpuDevice.cpp
@@ -7,14 +7,13 @@
 
 #include "SkGpuDevice.h"
 
-#include "GrBitmapTextContext.h"
 #include "GrContext.h"
-#include "GrDistanceFieldTextContext.h"
 #include "GrGpu.h"
 #include "GrGpuResourcePriv.h"
 #include "GrLayerHoister.h"
 #include "GrRecordReplaceDraw.h"
 #include "GrStrokeInfo.h"
+#include "GrTextContext.h"
 #include "GrTracing.h"
 #include "SkCanvasPriv.h"
 #include "SkDeviceImageFilterProxy.h"