Use StrictModeFlag in preparser and preparse data.

src/parser.h

Index: src/parser.h
diff --git a/src/parser.h b/src/parser.h
index 268b09474762c1f9e58dbbdbb01b0911da5e6e21..eaae6f7178a3cccb2da1dbcd3a7ec8dd319a3e81 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -76,7 +76,9 @@ class FunctionEntry BASE_EMBEDDED {
   int end_pos() { return backing_[kEndPosOffset]; }
   int literal_count() { return backing_[kLiteralCountOffset]; }
   int property_count() { return backing_[kPropertyCountOffset]; }
-  bool strict_mode() { return backing_[kStrictModeOffset] != 0; }
+  StrictModeFlag strict_mode_flag() {
+    return static_cast<StrictModeFlag>(backing_[kStrictModeOffset]);
+  }
 
   bool is_valid() { return backing_.length() > 0; }