Enable full type-checks in checked mode.

sdk/lib/_internal/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.
 
 part of ssa;
 
 class SsaCodeGeneratorTask extends CompilerTask {
 
   final JavaScriptBackend backend;
 
@@ skipping 2287 matching lines @@
     push(new js.Binary('&&',
                        objectTest,
                        new js.Binary('||', arrayTest, pop())));
   }
 
   void visitIs(HIs node) {
     DartType type = node.typeExpression;
     world.registerIsCheck(type, work.resolutionTree);
     HInstruction input = node.expression;
 
-    if (node.isVariableCheck || node.isCompoundCheck) {
+    if (node.isVariableCheck || node.isCompoundCheck ||
+        node.isCheckedModeTest) {
       use(node.checkCall);
     } else {
       assert(node.isRawCheck);
       LibraryElement coreLibrary = compiler.coreLibrary;
       ClassElement objectClass = compiler.objectClass;
       Element element = type.element;
 
       if (identical(element, objectClass) ||
           identical(element, compiler.dynamicClass)) {
         // The constant folder also does this optimization, but we make
@@ skipping 41 matching lines @@
       } else if (input.canBePrimitive(compiler) || input.canBeNull()) {
         checkObject(input, '===');
         js.Expression objectTest = pop();
         checkType(input, type);
         push(new js.Binary('&&', objectTest, pop()), node);
       } else {
         checkType(input, type);
         attachLocationToLast(node);
       }
     }
-    if (node.nullOk) {
+    if (!node.isCheckedModeTest && node.nullOk) {
       checkNull(input);
       push(new js.Binary('||', pop(), pop()), node);
     }
   }
 
   void visitTypeConversion(HTypeConversion node) {
     if (node.isChecked) {
       if (node.isArgumentTypeCheck) {
         if (node.isInteger()) {
           checkInt(node.checkedInput, '!==');
@@ skipping 580 matching lines @@
   if (leftType.canBeNull() && rightType.canBeNull()) {
     if (left.isConstantNull() || right.isConstantNull() ||
         (leftType.isPrimitive() && leftType == rightType)) {
       return '==';
     }
     return null;
   } else {
     return '===';
   }
 }