Don't allow oob message interrupts while executing constant expressions in the parser.

runtime/vm/compiler.cc

Index: runtime/vm/compiler.cc
diff --git a/runtime/vm/compiler.cc b/runtime/vm/compiler.cc
index 7c88444c94d75e6546c1e3abc203d1b617e42e50..1b597c24eabe7a8b987709aa569006c2a3d52961 100644
--- a/runtime/vm/compiler.cc
+++ b/runtime/vm/compiler.cc
@@ -1636,6 +1636,11 @@ RawObject* Compiler::ExecuteOnce(SequenceNode* fragment) {
   LongJumpScope jump;
   if (setjmp(*jump.Set()) == 0) {
     Thread* const thread = Thread::Current();
+    Isolate* const isolate = thread->isolate();
+
+    // Don't allow message interrupts while executing constant
+    // expressions.  They can cause bogus recursive compilation.
+    isolate->DeferMessageInterrupts();

[Cutch, 2016/02/09 17:05:51]

DBC: Consider adding a scope object helper class.

     if (FLAG_trace_compiler) {
       THR_Print("compiling expression: ");
       AstPrinter::PrintNode(fragment);
@@ -1682,6 +1687,7 @@ RawObject* Compiler::ExecuteOnce(SequenceNode* fragment) {
 
     const Object& result = PassiveObject::Handle(
         DartEntry::InvokeFunction(func, Object::empty_array()));
+    isolate->RestoreMessageInterrupts();
     return result.raw();
   } else {
     Thread* const thread = Thread::Current();
@@ -1689,6 +1695,7 @@ RawObject* Compiler::ExecuteOnce(SequenceNode* fragment) {
     const Object& result =
       PassiveObject::Handle(isolate->object_store()->sticky_error());
     isolate->object_store()->clear_sticky_error();
+    isolate->RestoreMessageInterrupts();
     return result.raw();
   }
   UNREACHABLE();