Issue 839: Bad code leading to top level methods being something other than identifier

compiler/java/com/google/dart/compiler/ast/LibraryUnit.java

Index: compiler/java/com/google/dart/compiler/ast/LibraryUnit.java
diff --git a/compiler/java/com/google/dart/compiler/ast/LibraryUnit.java b/compiler/java/com/google/dart/compiler/ast/LibraryUnit.java
index a5f4e33fb21d120314cafd5efe08bef2b6071310..00c24c92ae583852c8b12e97491072aecc76d115 100644
--- a/compiler/java/com/google/dart/compiler/ast/LibraryUnit.java
+++ b/compiler/java/com/google/dart/compiler/ast/LibraryUnit.java
@@ -308,8 +308,13 @@ public class LibraryUnit {
       public Void visitMethodDefinition(DartMethodDefinition node) {
         // Method names are always identifiers, except for factories, which cannot appear
         // in this context.
-        DartIdentifier name = (DartIdentifier) node.getName();
-        topLevelNodes.put(name.getTargetName(), node);
+        DartExpression name = node.getName();
+        if(name instanceof DartIdentifier) {
+          topLevelNodes.put(((DartIdentifier) name).getTargetName(), node);
+        } else {
+          // Visit the unknown node to generate a string for our use.
+          topLevelNodes.put(node.getName().toSource(), node);
+        }
         return null;
       }