Implement code generation for === and !==.

frog/leg/ssa/tracer.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.
 
 class HTracer extends HGraphVisitor {
   int indent = 0;
   final StringBuffer output;
 
   factory HTracer.singleton() {
     if (_singleton === null) _singleton = new HTracer._internal();
@@ skipping 189 matching lines @@
   String visitExit(HExit node) => "exit";
 
   String visitGoto(HGoto node) {
     HBasicBlock target = currentBlock.successors[0];
     return "Goto: (B${target.id})";
   }
 
   String visitGreater(HGreater node) => visitInvokeStatic(node);
   String visitGreaterEqual(HGreaterEqual node) => visitInvokeStatic(node);
 
+  String visitIdentity(HIdentity node) => visitInvokeStatic(node);
+
   String visitIf(HIf node) {
     HBasicBlock thenBlock = currentBlock.successors[0];
     HBasicBlock elseBlock = currentBlock.successors[1];
     String conditionId = temporaryId(node.inputs[0]);
     if (node.generateAtUseSite()) {
       String operation = "&&/||";
       if (elseBlock.first is HLogicalOperator) {
         HLogicalOperator op = elseBlock.first;
         operation = op.operation;
       }
@@ skipping 138 matching lines @@
       case HType.ARRAY: type = "array"; break;
       case HType.BOOLEAN: type = "bool"; break;
       case HType.NUMBER: type = "number"; break;
       case HType.STRING: type = "string"; break;
       case HType.STRING_OR_ARRAY: type = "string_or_array"; break;
       default: unreachable();
     }
     return "TypeGuard: ${temporaryId(node.inputs[0])} is $type";
   }
 }