Resolve op when op= syntax is used.

lib/compiler/implementation/elements/elements.dart

 // 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.
 
 #library('elements');
 
 #import('dart:uri');
 
 #import('../tree/tree.dart');
 #import('../scanner/scannerlib.dart');
@@ skipping 1637 matching lines @@
       // TODO(ahe): Remove this case: Legacy support for pre-0.11 spec.
       return selector;
     } else if (str === '?') {
       return selector;
     } else {
       throw new Exception('Unhandled selector: ${selector.slowToString()}');
     }
     return new SourceString('operator\$$str');
   }
 
+  static SourceString mapToUserOperator(SourceString op) {
+    String value = op.stringValue;
+
+    if (value === '!=') return const SourceString('==');
+    if (value === '*=') return const SourceString('*');
+    if (value === '/=') return const SourceString('/');
+    if (value === '%=') return const SourceString('%');
+    if (value === '~/=') return const SourceString('~/');
+    if (value === '+=') return const SourceString('+');
+    if (value === '-=') return const SourceString('-');
+    if (value === '<<=') return const SourceString('<<');
+    if (value === '>>=') return const SourceString('>>');
+    if (value === '&=') return const SourceString('&');
+    if (value === '^=') return const SourceString('^');
+    if (value === '|=') return const SourceString('|');
+
+    throw 'Unhandled operator: ${op.slowToString()}';
+  }
+
   static bool isNumberOrStringSupertype(Element element, Compiler compiler) {
     LibraryElement coreLibrary = compiler.coreLibrary;
     return (element == coreLibrary.find(const SourceString('Comparable')))
         || (element == coreLibrary.find(const SourceString('Hashable')));
   }
 
   static bool isStringOnlySupertype(Element element, Compiler compiler) {
     LibraryElement coreLibrary = compiler.coreLibrary;
     return element == coreLibrary.find(const SourceString('Pattern'));
   }
@@ skipping 124 matching lines @@
 
   MetadataAnnotation ensureResolved(Compiler compiler) {
     if (resolutionState == STATE_NOT_STARTED) {
       compiler.resolver.resolveMetadataAnnotation(this);
     }
     return this;
   }
 
   String toString() => 'MetadataAnnotation($value, $resolutionState)';
 }