Ensure that hashCode and runtimeType work on null.

lib/compiler/implementation/ssa/builder.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.
 
 class Interceptors {
   Compiler compiler;
   Interceptors(Compiler this.compiler);
 
   SourceString mapOperatorToMethodName(Operator op) {
     String name = op.source.stringValue;
@@ skipping 29 matching lines @@
     if (name === '^=') return const SourceString('xor');
     if (name === '++') return const SourceString('add');
     if (name === '--') return const SourceString('sub');
     compiler.unimplemented('Unknown operator', node: op);
   }
 
   // TODO(karlklose,kasperl): change uses of getStatic[Get|Set]Interceptor to
   // use this function.
   Element getStaticInterceptorBySelector(Selector selector) {
     if (selector.isGetter()) {
+      // TODO(lrn): If there is no get-interceptor, but there is a
+      // method-interceptor, we should generate a get-interceptor automatically.
       return getStaticGetInterceptor(selector.name);
     } else if (selector.isSetter()) {
       return getStaticSetInterceptor(selector.name);
     } else {
       return getStaticInterceptor(selector.name, selector.argumentCount);
     }
   }
 
   Element getStaticInterceptor(SourceString name, int parameters) {
     String mangledName = name.slowToString();
@@ skipping 4287 matching lines @@
           new HSubGraphBlockInformation(elseBranch.graph));
 
     HBasicBlock conditionStartBlock = conditionBranch.block;
     conditionStartBlock.setBlockFlow(info, joinBlock);
     SubGraph conditionGraph = conditionBranch.graph;
     HIf branch = conditionGraph.end.last;
     assert(branch is HIf);
     branch.blockInformation = conditionStartBlock.blockFlow;
   }
 }