Use Kernel frontend from run_vm_tests.

runtime/vm/unit_test.cc

Index: runtime/vm/unit_test.cc
diff --git a/runtime/vm/unit_test.cc b/runtime/vm/unit_test.cc
index 147d0eb73afce0358c8f37b00e447133a44d2de2..e7a468d3d814c1f533baaa159517d7ae5b16f434 100644
--- a/runtime/vm/unit_test.cc
+++ b/runtime/vm/unit_test.cc
@@ -28,6 +28,8 @@ using dart::bin::DartUtils;
 
 namespace dart {
 
+DECLARE_FLAG(bool, use_dart_frontend);
+
 TestCaseBase* TestCaseBase::first_ = NULL;
 TestCaseBase* TestCaseBase::tail_ = NULL;
 
@@ -258,11 +260,10 @@ static Dart_Handle LibraryTagHandler(Dart_LibraryTag tag,
   }
 }
 
-
-Dart_Handle TestCase::LoadTestScript(const char* script,
-                                     Dart_NativeEntryResolver resolver,
-                                     const char* lib_url,
-                                     bool finalize_classes) {
+static Dart_Handle LoadTestScriptWithVMParser(const char* script,
+                                              Dart_NativeEntryResolver resolver,
+                                              const char* lib_url,
+                                              bool finalize_classes) {
   Dart_Handle url = NewString(lib_url);
   Dart_Handle source = NewString(script);
   Dart_Handle result = Dart_SetLibraryTagHandler(LibraryTagHandler);
@@ -278,6 +279,50 @@ Dart_Handle TestCase::LoadTestScript(const char* script,
   return lib;
 }
 
+static char* Concat(const char* s1, const char* s2) {
+  int len = strlen(s1) + strlen(s2);
+  char* filename = new char[len + 1];
+  snprintf(filename, len + 1, "%s%s", s1, s2);
+  return filename;
+}

[siva, 2017/05/18 00:02:38]

The Concat function above may not be needed if you use OS::SCreate....

[aam, 2017/05/18 01:03:00]

Done.

+
+Dart_Handle TestCase::LoadTestScript(const char* script,
+                                     Dart_NativeEntryResolver resolver,
+                                     const char* lib_url,
+                                     bool finalize_classes) {
+  if (!FLAG_use_dart_frontend) {
+    return LoadTestScriptWithVMParser(script, resolver, lib_url,
+                                      finalize_classes);
+  }

[siva, 2017/05/18 00:02:38]

  Zone* zone = Thread::Current()->zone();

[aam, 2017/05/18 01:03:00]

Done.

+
+  char* filename = Concat("file:///", lib_url);

[siva, 2017/05/18 00:02:39]

char* filename = OS::SCreate(zone, "file:///", lib_url);

[aam, 2017/05/18 01:03:00]

Done.

+  // clang-format off
+  Dart_SourceFile sourcefiles[] = {
+    {
+      filename, script,
+    },
+    {
+      "file:///.packages", "untitled:/"
+    }};
+  // clang-format on
+
+  int sourcefiles_count = sizeof(sourcefiles) / sizeof(Dart_SourceFile);
+  Dart_KernelCompilationResult compilation_result =
+      Dart_CompileSourcesToKernel(filename, sourcefiles_count, sourcefiles);
+  delete[] filename;

[siva, 2017/05/18 00:02:38]

delete not needed as 'filename' would be zone allocated.

[aam, 2017/05/18 01:03:00]

Awesome, done!

+
+  EXPECT(compilation_result.status == Dart_KernelCompilationStatus_Ok)

[siva, 2017/05/18 00:02:38]

The EXPECT above would also print an error message, I think we can get rid of
the expect and just rely on your explicit check below.

[aam, 2017/05/18 01:03:01]

Right, done.

+  if (compilation_result.status != Dart_KernelCompilationStatus_Ok) {
+    OS::PrintErr("Compilation failed %s", compilation_result.error);
+    return NULL;

[siva, 2017/05/18 00:02:38]

should return a Dart_Handle not NULL

return Dart_ApiNewError(OS::SCreate(
    Thread::Current()->zone(), "Compilation failed %s",
compilation_result.error));

[aam, 2017/05/18 01:03:01]

Oh, nice! Done.

+  }
+  const uint8_t* kernel_file = compilation_result.kernel;
+  intptr_t kernel_length = compilation_result.kernel_size;
+  EXPECT(kernel_file != NULL);

[siva, 2017/05/18 00:02:38]

Should this be ASSERT(kernel_file != NULL);

or 
if (kernel_file == NULL) {
    return Dart_ApiNewError(OS::SCreate(Thread::Current()->zone(), "front end
generated a NULL kernel file"));
}

[aam, 2017/05/18 01:03:01]

Yes, I like this better!

+  void* kernel_program = Dart_ReadKernelBinary(kernel_file, kernel_length);
+  EXPECT(kernel_program != NULL);

[siva, 2017/05/18 00:02:38]

Ditto comment about this check here, should return a Dart_Handle

[aam, 2017/05/18 01:03:01]

Done!

+  return Dart_LoadKernel(kernel_program);
+}
 
 #ifndef PRODUCT