Replace boolean indications of strict mode by an enum value.

src/hydrogen.h

Index: src/hydrogen.h
diff --git a/src/hydrogen.h b/src/hydrogen.h
index 8ed112119ca97d26ae4a203179b3b0327a2d86ea..ec8afe6f039f318f031c1a4bb300fc2b8b4e2d9b 100644
--- a/src/hydrogen.h
+++ b/src/hydrogen.h
@@ -769,8 +769,8 @@ class HGraphBuilder: public AstVisitor {
   void ClearInlinedTestContext() {
     function_state()->ClearInlinedTestContext();
   }
-  bool function_strict_mode() {
-    return function_state()->compilation_info()->is_strict_mode();
+  StrictModeFlag function_strict_mode_flag() {
+    return function_state()->compilation_info()->strict_mode_flag();
   }
 
   // Generators for inline runtime functions.