Switch profiler from isolates to threads

runtime/vm/stub_code.cc

Index: runtime/vm/stub_code.cc
diff --git a/runtime/vm/stub_code.cc b/runtime/vm/stub_code.cc
index 7c8fe78127aa21da377f15a4d349287fe576d982..e9fffc249f241b02d82ac14957c99c7c3f7da2a7 100644
--- a/runtime/vm/stub_code.cc
+++ b/runtime/vm/stub_code.cc
@@ -79,7 +79,16 @@ void StubCode::VisitObjectPointers(ObjectPointerVisitor* visitor) {
 }
 
 
+bool StubCode::HasBeenInitialized() {
+  // Use JumpToExceptionHandler and InvokeDart as canaries.
+  const StubEntry* entry_1 = StubCode::JumpToExceptionHandler_entry();
+  const StubEntry* entry_2 = StubCode::InvokeDartCode_entry();
+  return (entry_1 != NULL) && (entry_2 != NULL);
+}
+
+
 bool StubCode::InInvocationStub(uword pc) {
+  ASSERT(HasBeenInitialized());
   uword entry = StubCode::InvokeDartCode_entry()->EntryPoint();
   uword size = StubCode::InvokeDartCodeSize();
   return (pc >= entry) && (pc < (entry + size));
@@ -87,6 +96,7 @@ bool StubCode::InInvocationStub(uword pc) {
 
 
 bool StubCode::InJumpToExceptionHandlerStub(uword pc) {
+  ASSERT(HasBeenInitialized());
   uword entry = StubCode::JumpToExceptionHandler_entry()->EntryPoint();
   uword size = StubCode::JumpToExceptionHandlerSize();
   return (pc >= entry) && (pc < (entry + size));