Generate escape sequence for non-printable ascii characters

runtime/vm/snapshot_test.cc

Index: runtime/vm/snapshot_test.cc
===================================================================
--- runtime/vm/snapshot_test.cc	(revision 35374)
+++ runtime/vm/snapshot_test.cc	(working copy)
@@ -860,7 +860,7 @@
     EXPECT_EQ(expected_kind, reconstructed_kind);
     expected_literal ^= expected_iterator.CurrentLiteral();
     actual_literal ^= reconstructed_iterator.CurrentLiteral();
-    EXPECT(expected_literal.Equals(actual_literal));
+    EXPECT_STREQ(expected_literal.ToCString(), actual_literal.ToCString());
     expected_iterator.Advance();
     reconstructed_iterator.Advance();
     expected_kind = expected_iterator.CurrentTokenKind();
@@ -908,6 +908,9 @@
       "d ${d} e\n"
       "g h i''';\n"
       "  }\n"
+      "  static ms6() {\n"
+      "    return '\\t \\n \\x00 \\xFF';\n"
+      "  }\n"
       "}\n";
 
   String& url = String::Handle(String::New("dart-test:SerializeScript"));