Fix string escape, recognize escaped newline

tests/language/language.status

 # Copyright (c) 2012, 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.
 
 # This directory contains tests that are intended to show the
 # current state of the language.
 
 # In order to maintain maximum test coverage for all builds,
 # please use the following procedure to mark a test
 # failed on architectures other than the one you are working on.
@@ skipping 35 matching lines @@
 ConstInit6NegativeTest: Fail       # Issue 811
 
 # Issue 905.
 TypeVariableBoundsTest/01: Fail
 TypeVariableBoundsTest/02: Fail
 TypeVariableBoundsTest/05: Fail
 TypeVariableBoundsTest/06: Fail
 TypeVariableBoundsTest/09: Fail
 TypeVariableBoundsTest/10: Fail
 
-# Issue 1350.
-StringEscape1NegativeTest: Fail
-StringEscape4NegativeTest: Fail
-
 SuperFirstConstructorTest: Fail # Issue 1372.
 
 # Issue 1427
 CyclicTypeVariableTest: Fail
 CyclicTypeVariableTest/01: Fail
 CyclicTypeVariableTest/02: Fail
 CyclicTypeVariableTest/03: Fail
 CyclicTypeVariableTest/04: Fail
 CyclicTypeVariableTest/05: Fail
 
@@ skipping 161 matching lines @@
 
 [ $component == frogsh || $component == webdriver || $component == frogium ]
 IntrinsifiedMethodsTest: Fail # Issue 1470
 ArithmeticTest: Fail # Issue 1470
 
 [ $component == frog ]
 ToStringAsFixedTest: Fail # fails due to rounding in constant propagation
 
 # This set of four test components (frog, frogsh, frogium, and webdriver) all
 # consume frog output, so if frog is generating the incorrect code, chances are
-# it will fail on all of these components. 
+# it will fail on all of these components.
 #
 # Further explanation:
 # frog: frog compiler, run using the VM
 # frogsh: self-hosted frog compiler
 # frogium: Dart code compiled with frogsh running under DumpRenderTree
-# webdriver: Dart code compiled with frogsh running on an actual browser 
+# webdriver: Dart code compiled with frogsh running on an actual browser
 # (Chrome, IE, Firefox, Safari, etc). If a test is only failing on a particular
 # browser, you can be more specific about the failure by using $browser:
 # [ $component == webdriver && $browser == chrome ] for example.
 [ $component == frog || $component == frogsh || $component == frogium || $component == webdriver]
 Factory3Test: Fail # Issue 417
 Factory2NegativeTest: Fail
 CallThroughNullGetterTest: Fail # Throw ObjectNotClosure instead of NullPointerException.
 ExtendTypeParameterNegativeTest: Skip # Issue 886
 ExtendTypeParameter2NegativeTest: Skip # Issue 886
 GetSetSyntaxTest/00: Fail # Issue 1571
@@ skipping 219 matching lines @@
 
 [ $component == frog && $mode == debug ]
 ConstructorRedirect1NegativeTest: Skip # Undiagnosed infinite loop.
 ConstructorRedirect2NegativeTest: Skip # Undiagnosed infinite loop.
 
 [ $arch == simarm ]
 *: Skip
 
 [ $arch == arm ]
 *: Skip