Add static_use to shader variable info query.

BUG=249018
ANGLEBUG=465
R=kbr@chromium.org

Review URL: https://codereview.appspot.com/13158043
diff --git a/src/compiler/Compiler.cpp b/src/compiler/Compiler.cpp
index 90065a6..0a91f9b 100644
--- a/src/compiler/Compiler.cpp
+++ b/src/compiler/Compiler.cpp
@@ -281,6 +281,7 @@
 
     attribs.clear();
     uniforms.clear();
+    varyings.clear();
 
     builtInFunctionEmulator.Cleanup();