Flag methods as not being valid compile time constants

compiler/java/com/google/dart/compiler/resolver/CompileTimeConstantAnalyzer.java

Index: compiler/java/com/google/dart/compiler/resolver/CompileTimeConstantAnalyzer.java
diff --git a/compiler/java/com/google/dart/compiler/resolver/CompileTimeConstantAnalyzer.java b/compiler/java/com/google/dart/compiler/resolver/CompileTimeConstantAnalyzer.java
index 352be8eebd1639e05a1a81cb3632e39062b79c3c..d84849e7ceed2cc87f3de9c2a7bc3a264ec723f3 100644
--- a/compiler/java/com/google/dart/compiler/resolver/CompileTimeConstantAnalyzer.java
+++ b/compiler/java/com/google/dart/compiler/resolver/CompileTimeConstantAnalyzer.java
@@ -320,6 +320,10 @@ public class CompileTimeConstantAnalyzer {
           rememberInferredType(x, type);
           break;
 
+        case METHOD:
+          expectedConstant(x);
+          return null;
+
         default:
           throw new InternalCompilerException("Unexpected element "
               + x.toString() + " kind: " + ElementKind.of(element)