Add dirty bits for the pixel pack and unpack buffer

BUG=605775

Change-Id: Ifb7eee94a395a9e9f5a5c1d6c0f05299162264a9
Reviewed-on: https://chromium-review.googlesource.com/340115
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
diff --git a/src/libANGLE/State.cpp b/src/libANGLE/State.cpp
index fb7d125..a1d2752 100644
--- a/src/libANGLE/State.cpp
+++ b/src/libANGLE/State.cpp
@@ -1069,11 +1069,13 @@
 void State::setPixelPackBufferBinding(Buffer *buffer)
 {
     mPack.pixelBuffer.set(buffer);
+    mDirtyBits.set(DIRTY_BIT_PACK_BUFFER_BINDING);
 }
 
 void State::setPixelUnpackBufferBinding(Buffer *buffer)
 {
     mUnpack.pixelBuffer.set(buffer);
+    mDirtyBits.set(DIRTY_BIT_UNPACK_BUFFER_BINDING);
 }
 
 Buffer *State::getTargetBuffer(GLenum target) const