Generate outline without transformations in patched_sdk, use it for unit tests

tools/patch_sdk.dart

Index: tools/patch_sdk.dart
diff --git a/tools/patch_sdk.dart b/tools/patch_sdk.dart
index 24e9cf7472e51e5ffaa8540451c3f0c9b3921b36..425e68f093a5281fb227174a6e73c1d7171065b2 100644
--- a/tools/patch_sdk.dart
+++ b/tools/patch_sdk.dart
@@ -104,11 +104,14 @@ Future _main(List<String> argv) async {
   if (forVm) _copyExtraVmLibraries(sdkOut);
 
   Uri platform = outDirUri.resolve('platform.dill.tmp');
+  Uri outline = outDirUri.resolve('outline.dill');
   Uri packages = Uri.base.resolveUri(new Uri.file(packagesFile));
   if (forVm) {
-    await fasta.compilePlatform(outDirUri, platform, packages: packages);
+    await fasta.compilePlatform(outDirUri, platform,
+        packages: packages, outlineOutput: outline);
   } else {
-    await dart2js.compilePlatform(outDirUri, platform, packages: packages);
+    await dart2js.compilePlatform(outDirUri, platform,
+        packages: packages, outlineOutput: outline);
   }
 
   Uri platformFinalLocation = outDirUri.resolve('platform.dill');