Move some D3D-specific stuff into ProgramD3D.

BUG=angle:773

Change-Id: I48b42e7a3e82a43d3dde16a8d1016d28280eae39
Reviewed-on: https://chromium-review.googlesource.com/232968
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>
diff --git a/src/libANGLE/renderer/ProgramImpl.cpp b/src/libANGLE/renderer/ProgramImpl.cpp
index b4dfc45..8fbc537 100644
--- a/src/libANGLE/renderer/ProgramImpl.cpp
+++ b/src/libANGLE/renderer/ProgramImpl.cpp
@@ -142,6 +142,7 @@
 
 void ProgramImpl::reset()
 {
+    std::fill(mSemanticIndex, mSemanticIndex + ArraySize(mSemanticIndex), -1);
     SafeDeleteContainer(mUniforms);
     mUniformIndex.clear();
     SafeDeleteContainer(mUniformBlocks);