Don't generate errors when failing to follow const constructor redirections.

editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/object/NumState.java

Index: editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/object/NumState.java
diff --git a/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/object/NumState.java b/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/object/NumState.java
index fae41c21c2b43d7b63fa5bb883e3fab97db24c3b..10589777e9956d88f3a3a127bd1d4d216bcc764b 100644
--- a/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/object/NumState.java
+++ b/editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/object/NumState.java
@@ -53,17 +53,17 @@ public class NumState extends InstanceState {
   }
 
   @Override
-  public boolean equals(Object object) {
-    return object instanceof NumState;
-  }
-
-  @Override
   public BoolState equalEqual(InstanceState rightOperand) throws EvaluationException {
     assertBoolNumStringOrNull(rightOperand);
     return BoolState.UNKNOWN_VALUE;
   }
 
   @Override
+  public boolean equals(Object object) {
+    return object instanceof NumState;
+  }
+
+  @Override
   public String getTypeName() {
     return "num"; //$NON-NLS-0$
   }
@@ -107,6 +107,11 @@ public class NumState extends InstanceState {
   }
 
   @Override
+  public boolean isUnknown() {
+    return this == UNKNOWN_VALUE;
+  }
+
+  @Override
   public BoolState lessThan(InstanceState rightOperand) throws EvaluationException {
     assertNumOrNull(rightOperand);
     return BoolState.UNKNOWN_VALUE;