Reapply "Tweak public APIs and use them in patch_sdk, dart2js, and kernel-service.""

pkg/front_end/test/fasta/testing/suite.dart

Index: pkg/front_end/test/fasta/testing/suite.dart
diff --git a/pkg/front_end/test/fasta/testing/suite.dart b/pkg/front_end/test/fasta/testing/suite.dart
index ed6c64dc864660be9d018792e5d60b3cbbe53569..37acdba90a8109556f30caa3d5c75fe25581a0f3 100644
--- a/pkg/front_end/test/fasta/testing/suite.dart
+++ b/pkg/front_end/test/fasta/testing/suite.dart
@@ -98,7 +98,7 @@ class FastaContext extends ChainContext {
   Uri sdk;
   Uri platformUri;
   Uri outlineUri;
-  List<int> outlineBytes;
+  Program outline;
 
   final ExpectationSet expectationSet =
       new ExpectationSet.fromJsonList(JSON.decode(EXPECTATIONS));
@@ -139,15 +139,12 @@ class FastaContext extends ChainContext {
   }
 
   Future<Program> loadPlatformOutline() async {
-    if (outlineBytes == null) {
+    if (outline == null) {
       await ensurePlatformUris();
-      outlineBytes = new File.fromUri(outlineUri).readAsBytesSync();
+      outline =
+          loadProgramFromBytes(new File.fromUri(outlineUri).readAsBytesSync());
     }
-    // Note: we rebuild the platform outline on every test because the compiler
-    // currently mutates the in-memory representation of the program without
-    // cloning it.
-    // TODO(sigmund): investigate alternatives to this approach.
-    return loadProgramFromBytes(outlineBytes);
+    return outline;
   }
 
   static Future<FastaContext> create(
@@ -259,7 +256,7 @@ class Outline extends Step<TestDescription, Program, FastaContext> {
       }
       p = await sourceTarget.buildOutlines();
       if (fullCompile) {
-        p = await sourceTarget.buildProgram(trimDependencies: true);
+        p = await sourceTarget.buildProgram();
         instrumentation?.finish();
         if (instrumentation != null && instrumentation.hasProblems) {
           if (updateComments) {