Disable GL_OES_standard_derivatives when ps_2_x or later is not available.

BUG=392
Review URL: https://codereview.appspot.com/7027051


Author:    bsalomon@google.com

(manual merge from master by daniel@transgaming.com)

git-svn-id: https://angleproject.googlecode.com/svn/branches/dx11proto@1704 736b8ea6-26fd-11df-bfd4-992fa37f6226
diff --git a/src/libGLESv2/renderer/Renderer9.cpp b/src/libGLESv2/renderer/Renderer9.cpp
index 7b23c94..e0b1b8c 100644
--- a/src/libGLESv2/renderer/Renderer9.cpp
+++ b/src/libGLESv2/renderer/Renderer9.cpp
@@ -2211,6 +2211,11 @@
     return (mD3d9Ex != NULL) && !gl::perfActive();
 }
 
+bool Renderer9::getDerivativeInstructionSupport() const
+{
+    return (mDeviceCaps.PS20Caps.Caps & D3DPS20CAPS_GRADIENTINSTRUCTIONS) != 0;
+}
+
 int Renderer9::getMajorShaderModel() const
 {
     return D3DSHADER_VERSION_MAJOR(mDeviceCaps.PixelShaderVersion);