dart2js: emit tear-offs in new emitter.

sdk/lib/_internal/compiler/js_lib/js_helper.dart

Index: sdk/lib/_internal/compiler/js_lib/js_helper.dart
diff --git a/sdk/lib/_internal/compiler/js_lib/js_helper.dart b/sdk/lib/_internal/compiler/js_lib/js_helper.dart
index 97b1a9d9ef1a2dcf9162f8dd4af58573679c137d..7d06ee2634b52a072e4fd40fb372663c3f44b6e1 100644
--- a/sdk/lib/_internal/compiler/js_lib/js_helper.dart
+++ b/sdk/lib/_internal/compiler/js_lib/js_helper.dart
@@ -1964,7 +1964,7 @@ abstract class Closure implements Function {
    */
   static fromTearOff(receiver,
                      List functions,
-                     List reflectionInfo,
+                     var reflectionInfo,
                      bool isStatic,
                      jsArguments,
                      String propertyName) {
@@ -1978,10 +1978,15 @@ abstract class Closure implements Function {
     String name = JS('String|Null', '#.\$stubName', function);
     String callName = JS('String|Null', '#.\$callName', function);
 
-    JS('', '#.\$reflectionInfo = #', function, reflectionInfo);
-    ReflectionInfo info = new ReflectionInfo(function);
+    var functionType;
+    if (reflectionInfo is List) {
+      JS('', '#.\$reflectionInfo = #', function, reflectionInfo);
+      ReflectionInfo info = new ReflectionInfo(function);
+      functionType = info.functionType;
+    } else {
+      functionType = reflectionInfo;
+    }
 
-    var functionType = info.functionType;
 
     // function tmp() {};
     // tmp.prototype = BC.prototype;
@@ -2064,7 +2069,8 @@ abstract class Closure implements Function {
             'return f.apply({\$receiver:r(this)},arguments)'
           '}'
         '}(#,#)', functionType, getReceiver);
-    } else {
+    } else if (functionType != null) {
+      // TODO(herhut): Disallow null again once we have function types.
       throw 'Error in reflectionInfo.';
     }
 
@@ -2323,7 +2329,7 @@ closureFromTearOff(receiver,
   return Closure.fromTearOff(
       receiver,
       JSArray.markFixedList(functions),
-      JSArray.markFixedList(reflectionInfo),
+      reflectionInfo is List ? JSArray.markFixedList(reflectionInfo) : reflectionInfo,
       JS('bool', '!!#', isStatic),
       jsArguments,
       JS('String', '#', name));