Fix a couple forward declares in angletypes.h.

These were vestigal from previous code.

BUG=angleproject:1593

Change-Id: I1d9a8e6f60d1dadf8a8a598bdbddd98457eb559c
Reviewed-on: https://chromium-review.googlesource.com/442651
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
diff --git a/src/libANGLE/Program.h b/src/libANGLE/Program.h
index 5a638df..d1d131a 100644
--- a/src/libANGLE/Program.h
+++ b/src/libANGLE/Program.h
@@ -44,6 +44,7 @@
 class ContextState;
 class Shader;
 class ShaderProgramManager;
+class State;
 class InfoLog;
 class Buffer;
 class Framebuffer;