Fix intermittent simarm build breakage on macos.

vm/class_finalizer.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/class_finalizer.h"
 
 #include "vm/flags.h"
 #include "vm/heap.h"
 #include "vm/isolate.h"
 #include "vm/longjump.h"
@@ skipping 493 matching lines @@
   if (type_class.IsSignatureClass()) {
     ResolveAndFinalizeSignature(
         type_class, Function::Handle(type_class.signature_function()));
   }
 
   parameterized_type.set_is_finalized();
 }
 
 
 RawString* ClassFinalizer::FinalizeTypeWhileParsing(const Type& type) {
-  String& msg = String::Handle();
   Isolate* isolate = Isolate::Current();
   ASSERT(isolate != NULL);
   LongJump* base = isolate->long_jump_base();
   LongJump jump;
   isolate->set_long_jump_base(&jump);
   if (setjmp(*jump.Set()) == 0) {
     FinalizeType(type);
+    isolate->set_long_jump_base(base);
+    return String::null();
   } else {
     // Error occured: Get the error message.
-    msg = isolate->object_store()->sticky_error();
+    isolate->set_long_jump_base(base);
+    return isolate->object_store()->sticky_error();
   }
-  isolate->set_long_jump_base(base);
-  return msg.raw();
+  UNREACHABLE();
+  return String::null();
 }
 
 
 // Top level function signatures are canonicalized, added to the library class
 // dictionary, and finalized with other library classes and interfaces.
 // Function signatures used as type of a local variable or of a local function
 // are canonicalized and finalized upon creation, since all the types they
 // reference are already resolved.
 void ClassFinalizer::ResolveAndFinalizeSignature(const Class& cls,
                                                  const Function& function) {
@@ skipping 445 matching lines @@
   ASSERT(msg_buffer != NULL);
   va_list args;
   va_start(args, format);
   OS::VSNPrint(msg_buffer, kBufferLength, format, args);
   va_end(args);
   isolate->long_jump_base()->Jump(1, msg_buffer);
   UNREACHABLE();
 }
 
 }  // namespace dart