Fixed analyzer test to use dart2js not dartium

tools/patch_sdk.dart

Index: tools/patch_sdk.dart
diff --git a/tools/patch_sdk.dart b/tools/patch_sdk.dart
index 0f7b10aed65317312621a5bbded00daff2a50a08..ec5d4ab10a892e10e1a8d47a7cec12f1bc4c9ec0 100644
--- a/tools/patch_sdk.dart
+++ b/tools/patch_sdk.dart
@@ -43,7 +43,8 @@ final deps = new Set<Uri>();
 File getInputFile(String path, {canBeMissing: false}) {
   final file = new File(path);
   if (!file.existsSync()) {
-    if (!canBeMissing) throw "patch_sdk.dart expects all inputs to exist";
+    if (!canBeMissing)
+      throw "patch_sdk.dart expects all inputs to exist, missing: $path";
     return null;
   }
   deps.add(Uri.base.resolveUri(file.uri));