Add Dart_GetStickyError

runtime/vm/dart_api_impl.cc

Index: runtime/vm/dart_api_impl.cc
diff --git a/runtime/vm/dart_api_impl.cc b/runtime/vm/dart_api_impl.cc
index ff628394146695e41eaba62d2a1ff6699da0a638..ddf29f343980accf3c49b434d761003bcfaf9d5a 100644
--- a/runtime/vm/dart_api_impl.cc
+++ b/runtime/vm/dart_api_impl.cc
@@ -1467,11 +1467,11 @@ DART_EXPORT void Dart_SetStickyError(Dart_Handle error) {
   Isolate* isolate = thread->isolate();
   CHECK_ISOLATE(isolate);
   NoSafepointScope no_safepoint_scope;
-  if (isolate->sticky_error() != Error::null()) {
+  if ((isolate->sticky_error() != Error::null()) && !::Dart_IsNull(error)) {
     FATAL1("%s expects there to be no sticky error.", CURRENT_FUNC);
   }
-  if (!::Dart_IsUnhandledExceptionError(error)) {
-    FATAL1("%s expects the error to be an unhandled exception error.",
+  if (!::Dart_IsUnhandledExceptionError(error) && !::Dart_IsNull(error)) {
+    FATAL1("%s expects the error to be an unhandled exception error or null.",
             CURRENT_FUNC);
   }
   isolate->SetStickyError(
@@ -1487,6 +1487,19 @@ DART_EXPORT bool Dart_HasStickyError() {
 }
 
 
+DART_EXPORT Dart_Handle Dart_GetStickyError() {
+  Isolate* I = Isolate::Current();
+  CHECK_ISOLATE(I);

[siva, 2016/09/22 19:43:54]

Other places we use the pattern
  Thread* T = Thread::Current();
  Isolate* I = T->isolate();
  CHECK_ISOLATE(I);
  .....
Then T is available to use inside the function instead of Thread::Current();

+  NoSafepointScope no_safepoint_scope;
+  if (I->sticky_error() != Object::null()) {

[siva, 2016/09/22 19:43:54]

if (I->sticky_error() != Error::null()) {

+    Dart_Handle error =
+        Api::NewHandle(Thread::Current(), I->sticky_error());

[siva, 2016/09/22 19:43:54]

NewHandle(T, ...);

+    return error;
+  }
+  return Dart_Null();
+}
+
+
 DART_EXPORT void Dart_ExitIsolate() {
   Thread* T = Thread::Current();
   CHECK_ISOLATE(T->isolate());