Add support for glMapBufferRange. Use glMapBufferRange and glMapBufferSubData.

src/gpu/gl/angle/GrGLCreateANGLEInterface.cpp

Index: src/gpu/gl/angle/GrGLCreateANGLEInterface.cpp
diff --git a/src/gpu/gl/angle/GrGLCreateANGLEInterface.cpp b/src/gpu/gl/angle/GrGLCreateANGLEInterface.cpp
index a316ff1c11913c6c8eb82822e9535577019f213b..cb2fc953365ed98fe6634aebe25eec67596bbc4a 100644
--- a/src/gpu/gl/angle/GrGLCreateANGLEInterface.cpp
+++ b/src/gpu/gl/angle/GrGLCreateANGLEInterface.cpp
@@ -154,6 +154,14 @@ const GrGLInterface* GrGLCreateANGLEInterface() {
     functions->fMapBuffer = (GrGLMapBufferProc) eglGetProcAddress("glMapBufferOES");
     functions->fUnmapBuffer = (GrGLUnmapBufferProc) eglGetProcAddress("glUnmapBufferOES");
 
+#if GL_ES_VERSION_3_0
+    functions->fMapBufferRange = GET_PROC(glMapBufferRange);
+    functions->fFlushMappedBufferRange = GET_PROC(glFlushMappedBufferRange);
+#else
+    functions->fMapBufferRange = (GrGLMapBufferRangeProc) eglGetProcAddress("glMapBufferRange");
+    functions->fFlushMappedBufferRange = (GrGLFlushMappedBufferRangeProc) eglGetProcAddress("glFlushMappedBufferRange");
+#endif
+
     functions->fInsertEventMarker = (GrGLInsertEventMarkerProc) eglGetProcAddress("glInsertEventMarkerEXT");
     functions->fPushGroupMarker = (GrGLInsertEventMarkerProc) eglGetProcAddress("glPushGroupMarkerEXT");
     functions->fPopGroupMarker = (GrGLPopGroupMarkerProc) eglGetProcAddress("glPopGroupMarkerEXT");