Fix DDC errors on DDC

lib/src/checker/checker.dart

Index: lib/src/checker/checker.dart
diff --git a/lib/src/checker/checker.dart b/lib/src/checker/checker.dart
index b114ba08c4402fcf1fe0d4b47aeec86e72bf7afb..b503c29fde18c404f077fd62099b555ea7d51636 100644
--- a/lib/src/checker/checker.dart
+++ b/lib/src/checker/checker.dart
@@ -227,10 +227,11 @@ class _OverrideChecker {
       if (member is FieldDeclaration) {
         if (member.isStatic) continue;
         for (var variable in member.fields.variables) {
-          var name = variable.element.name;
+          var element = variable.element as PropertyInducingElement;

[Jennifer Messerly, 2015/06/01 21:52:10]

random Q, do we always prefer this pattern over:

PropertyInducingElement element = variable.element;

?

reason I ask, it's 7 chars shorter ("var_as_"), which is almost 10% of line
length or 3.5 indent levels

[vsm, 2015/06/01 22:44:19]

I lean toward the rhs version - it makes it explicit that there is a cast going
on and that cast would appear in generated JS.

[Jennifer Messerly, 2015/06/01 23:10:56]

err, wouldn't we generate a cast in JS for both cases?

+          var name = element.name;
           if (seen.contains(name)) continue;
-          var getter = variable.element.getter;
-          var setter = variable.element.setter;
+          var getter = element.getter;
+          var setter = element.setter;
           bool found = _checkSingleOverride(getter, baseType, variable, member);
           if (!variable.isFinal &&
               _checkSingleOverride(setter, baseType, variable, member)) {
@@ -238,14 +239,15 @@ class _OverrideChecker {
           }
           if (found) seen.add(name);
         }
-      } else {
-        assert(member is MethodDeclaration);
+      } else if (member is MethodDeclaration) {
         if (member.isStatic) continue;
         var method = member.element;

[Jennifer Messerly, 2015/06/01 21:52:10]

instead of changing the if structure, maybe

  var method = (member as MethodDeclaration).element;

then no assert needed

[vsm, 2015/06/01 22:44:19]

It's actually on isStatic, but done there.

         if (seen.contains(method.name)) continue;
         if (_checkSingleOverride(method, baseType, member, member)) {
           seen.add(method.name);
         }
+      } else {
+        assert(false);
       }
     }
   }