Implement 'as' operator.

lib/compiler/implementation/ssa/codegen.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 SsaCodeGeneratorTask extends CompilerTask {
   final JavaScriptBackend backend;
   SsaCodeGeneratorTask(JavaScriptBackend backend)
       : this.backend = backend,
         super(backend.compiler);
   String get name() => 'SSA code generator';
@@ skipping 2217 matching lines @@
         buffer.add(".${name.slowToString()} === '${arguments.head}'");
         endExpression(JSPrecedence.LOGICAL_AND_PRECEDENCE);
       });
     }
     if (node.nullOk) {
       endExpression(JSPrecedence.LOGICAL_OR_PRECEDENCE);
     }
   }
 
   void visitTypeConversion(HTypeConversion node) {
+    Map<String, SourceString> castNames = const <SourceString> {
+      "stringTypeCheck":
+          const SourceString("stringTypeCast"),
+      "doubleTypeCheck":
+          const SourceString("doubleTypeCast"),
+      "numTypeCheck":
+          const SourceString("numTypeCast"),
+      "boolTypeCheck":
+          const SourceString("boolTypeCast"),
+      "functionTypeCheck":
+          const SourceString("functionTypeCast"),
+      "intTypeCheck":
+          const SourceString("intTypeCast"),
+      "stringSuperNativeTypeCheck":
+          const SourceString("stringSuperNativeTypeCast"),
+      "stringSuperTypeCheck":
+          const SourceString("stringSuperTypeCast"),
+      "listTypeCheck":
+          const SourceString("listTypeCast"),
+      "listSuperNativeTypeCheck":
+          const SourceString("listSuperNativeTypeCast"),
+      "listSuperTypeCheck":
+          const SourceString("listSuperTypeCast"),
+      "callTypeCheck":
+          const SourceString("callTypeCast"),
+      "propertyTypeCheck":
+          const SourceString("propertyTypeCast")
+    };
     if (node.checked) {
       Element element = node.type.computeType(compiler).element;
       world.registerIsCheck(element);
       SourceString helper;
       String additionalArgument;
       bool nativeCheck =
           backend.emitter.nativeEmitter.requiresNativeIsCheck(element);
       beginExpression(JSPrecedence.CALL_PRECEDENCE);
 
       if (element == compiler.stringClass) {
@@ skipping 23 matching lines @@
             helper = const SourceString('listSuperNativeTypeCheck');
           } else {
             helper = const SourceString('listSuperTypeCheck');
           }
         } else if (nativeCheck) {
           helper = const SourceString('callTypeCheck');
         } else {
           helper = const SourceString('propertyTypeCheck');
         }
       }
+      if (node.isCast) {
+        helper = castNames[helper.stringValue];
+      }
       Element helperElement = compiler.findHelper(helper);
       world.registerStaticUse(helperElement);
       buffer.add(compiler.namer.isolateAccess(helperElement));
       buffer.add('(');
       use(node.checkedInput, JSPrecedence.EXPRESSION_PRECEDENCE);
       if (additionalArgument !== null) buffer.add(", '$additionalArgument'");
       buffer.add(')');
       endExpression(JSPrecedence.CALL_PRECEDENCE);
     } else {
       use(node.checkedInput, expectedPrecedence);
@@ skipping 388 matching lines @@
       startBailoutSwitch();
     }
   }
 
   void endLabeledBlock(HLabeledBlockInformation labeledBlockInfo) {
     if (labeledBlockInfo.body.start.hasGuards()) {
       endBailoutSwitch();
     }
   }
 }