Scanner: disallow unicode escapes in regexp flags.

test/cctest/test-parsing.cc

Index: test/cctest/test-parsing.cc
diff --git a/test/cctest/test-parsing.cc b/test/cctest/test-parsing.cc
index 1909b3e66b4039c3e2548bad2256e1d06d3b6a84..79d76546e90b117404d191bcf59bfa2f33ec5c20 100644
--- a/test/cctest/test-parsing.cc
+++ b/test/cctest/test-parsing.cc
@@ -4302,7 +4302,9 @@ TEST(InvalidUnicodeEscapes) {
     "var foob\\u123r = 0;",
     "var \\u123roo = 0;",
     "\"foob\\u123rr\"",
-    "/regex/g\\u123r",
+    // No escapes allowed in regexp flags
+    "/regex/\\u0069g",
+    "/regex/\\u006g",
     NULL};
   RunParserSyncTest(context_data, data, kError);
 }