Handle escapes in string literals.

frog/tests/leg/src/BuiltinInterceptorTest.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #import("compiler_helper.dart");
 
 final String TEST_ONE = @"""
 foo(String a) {
   return a.length;
 }
 """;
 
 final String TEST_TWO = @"""
 foo() {
   return "foo".length;
 }
 """;
 
 final String TEST_THREE = @"""
 foo() {
   return @"foo".length;
 }
 """;
 
 main() {
   String generated = compile(TEST_ONE, 'foo');
   Expect.isTrue(generated.contains("return a.length;"));
 
-  // TODO(ngeoffray): Enable once we support raw strings
-  // and folding of length.
-  Exception exception;
-  try {
-    generated = compile(TEST_TWO, 'foo');
-    Expect.isTrue(generated.contains("return 3;"));
+  // TODO(lrn): Switch these two to isTrue when we support constant folding
+  // of string length.
+  generated = compile(TEST_TWO, 'foo');
+  Expect.isFalse(generated.contains("return 3;"));
 
-    generated = compile(TEST_THREE, 'foo');
-    Expect.isTrue(generated.contains("return 3;"));
-  } catch (var e) {
-    exception = e;
-  }
-  Expect.isTrue(exception != null);
+  generated = compile(TEST_THREE, 'foo');
+  Expect.isFalse(generated.contains("return 3;"));
 }