Changes "is" and equality checks to strictly check for primitive types, fix a couple of

compiler/lib/implementation/number.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 NumberImplementation implements int, double native "Number" {
   NumberImplementation operator +(NumberImplementation other) native;
   NumberImplementation operator -(NumberImplementation other) native;
   NumberImplementation operator *(NumberImplementation other) native;
   NumberImplementation operator /(NumberImplementation other) native;
   NumberImplementation operator ~/(NumberImplementation other) native;
@@ skipping 37 matching lines @@
   int toInt() {
     if (isNaN()) throw new BadNumberFormatException("NaN");
     if (isInfinite()) throw new BadNumberFormatException("Infinity");
     NumberImplementation truncated = truncate();
     // If truncated is -0.0 return +0. The test will also trigger for positive
     // 0s but that's not a problem.
     if (truncated == -0.0) return 0;
     return truncated;
   }
 
-  NumberImplementation toDouble() { return this; }
-
+  NumberImplementation toDouble() native;
   String toString() native;
   String toStringAsFixed(int fractionDigits) native;
   String toStringAsExponential(int fractionDigits) native;
   String toStringAsPrecision(int precision) native;
   String toRadixString(int radix) native;
 
   int hashCode() native;
+  get dynamic() { return toDouble(); }
 }