Detect total switches to prevent type pollution by default cases.

sdk/lib/_internal/compiler/implementation/constants.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 dart2js;
 
 abstract class ConstantVisitor<R> {
   R visitFunction(FunctionConstant constant);
   R visitNull(NullConstant constant);
   R visitInt(IntConstant constant);
@@ skipping 524 matching lines @@
 
   accept(ConstantVisitor visitor) => visitor.visitInterceptor(this);
 
   DartType computeType(Compiler compiler) => compiler.types.dynamicType;
 
   ti.TypeMask computeMask(Compiler compiler) {
     return compiler.typesTask.nonNullType;
   }
 
   String toString() {
-    return 'InterceptorConstant(${Error.safeToString(dispatchedType)})';
+    return 'InterceptorConstant(${dispatchedType.getStringAsDeclared("o")})';
   }
 }
 
 class DummyConstant extends Constant {
   final ti.TypeMask typeMask;
 
   DummyConstant(this.typeMask);
 
   bool isDummy() => true;
 
@@ skipping 83 matching lines @@
       if (i > 0) sb.write(',');
       sb.write(Error.safeToString(field.name));
       sb.write('=');
       sb.write(Error.safeToString(value));
       i++;
     });
     sb.write('))');
     return sb.toString();
   }
 }