Add gpu support for glVertexAttrb1f, 2fv, and 3fv

BUG=skia:

Review URL: https://codereview.chromium.org/662583003
diff --git a/include/gpu/gl/GrGLInterface.h b/include/gpu/gl/GrGLInterface.h
index 32552e6..5a4b1e7 100644
--- a/include/gpu/gl/GrGLInterface.h
+++ b/include/gpu/gl/GrGLInterface.h
@@ -311,6 +311,9 @@
         GLPtr<GrGLUnmapBufferSubDataProc> fUnmapBufferSubData;
         GLPtr<GrGLUnmapTexSubImage2DProc> fUnmapTexSubImage2D;
         GLPtr<GrGLUseProgramProc> fUseProgram;
+        GLPtr<GrGLVertexAttrib1fProc> fVertexAttrib1f;
+        GLPtr<GrGLVertexAttrib2fvProc> fVertexAttrib2fv;
+        GLPtr<GrGLVertexAttrib3fvProc> fVertexAttrib3fv;
         GLPtr<GrGLVertexAttrib4fvProc> fVertexAttrib4fv;
         GLPtr<GrGLVertexAttribPointerProc> fVertexAttribPointer;
         GLPtr<GrGLViewportProc> fViewport;