Move LookupResult into crankshaft as that's now the only place where it's still used

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index 8c3fce930ed6732c281a46ed83cd30a915a52b39..a1a6f4f794fdf5dd71c43de96539c1e96e6d82ac 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -83,7 +83,6 @@ void ThreadLocalTop::InitializeInternal() {
   failed_access_check_callback_ = NULL;
   save_context_ = NULL;
   catcher_ = NULL;
-  top_lookup_result_ = NULL;
   promise_on_stack_ = NULL;
 
   // These members are re-initialized later after deserialization
@@ -207,9 +206,6 @@ void Isolate::Iterate(ObjectVisitor* v, ThreadLocalTop* thread) {
   for (StackFrameIterator it(this, thread); !it.done(); it.Advance()) {
     it.frame()->Iterate(v);
   }
-
-  // Iterate pointers in live lookup results.
-  thread->top_lookup_result_->Iterate(v);
 }