Fix background compilation: allocate stubs at safepoint

runtime/vm/compiler.cc

 // Copyright (c) 2012, 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/compiler.h"
 
 #include "vm/assembler.h"
 
 #include "vm/ast_printer.h"
 #include "vm/block_scheduler.h"
@@ skipping 1135 matching lines @@
         FLAG_trace_compiler ||
         (FLAG_trace_optimizing_compiler && optimized);
     Timer per_compile_timer(trace_compiler, "Compilation time");
     per_compile_timer.Start();
 
     ParsedFunction* parsed_function = new(zone) ParsedFunction(
         thread, Function::ZoneHandle(zone, function.raw()));
     if (trace_compiler) {
       const intptr_t token_size = function.end_token_pos().Pos() -
                                   function.token_pos().Pos();
-      THR_Print("Compiling %s%sfunction: '%s' @ token %s, size %" Pd "\n",
+      THR_Print("Compiling %s%sfunction %s: '%s' @ token %s, size %" Pd "\n",
                 (osr_id == Compiler::kNoOSRDeoptId ? "" : "osr "),
                 (optimized ? "optimized " : ""),
+                (Compiler::IsBackgroundCompilation() ? "(background)" : ""),
                 function.ToFullyQualifiedCString(),
                 function.token_pos().ToCString(),
                 token_size);
     }
     INC_STAT(thread, num_functions_compiled, 1);
     if (optimized) {
       INC_STAT(thread, num_functions_optimized, 1);
     }
     {
       HANDLESCOPE(thread);
@@ skipping 718 matching lines @@
 }
 
 
 void BackgroundCompiler::EnsureInit(Thread* thread) {
   UNREACHABLE();
 }
 
 #endif  // DART_PRECOMPILED_RUNTIME
 
 }  // namespace dart