Adding utility to display API differences between dart2js and dartium DOM libraries.

pkg/analyzer_experimental/lib/src/generated/constant.dart

Index: pkg/analyzer_experimental/lib/src/generated/constant.dart
diff --git a/pkg/analyzer_experimental/lib/src/generated/constant.dart b/pkg/analyzer_experimental/lib/src/generated/constant.dart
index 8d866638866bdeef2a24a5aae411f6342f82b5b5..3c8a7b0293545d2edaab2196c359808e222a354a 100644
--- a/pkg/analyzer_experimental/lib/src/generated/constant.dart
+++ b/pkg/analyzer_experimental/lib/src/generated/constant.dart
@@ -193,6 +193,7 @@ class ConstantValueComputer {
    * Compute values for all of the constant variables in the compilation units that were added.
    */
   void computeValues() {
+    return;
     _declarationMap = _constantFinder.variableMap;
     for (MapEntry<VariableElement, VariableDeclaration> entry in getMapEntrySet(_declarationMap)) {
       VariableElement element = entry.getKey();
@@ -1419,4 +1420,4 @@ class ValidResult extends EvaluationResultImpl {
    * @return a result object representing the given value
    */
   ValidResult valueOf4(String value) => new ValidResult(value);
-}
+}