[cleanup] Properly tail call from GrowArrayElementsStub.

Now that Crankshaft is gone we no longer need to worry about parameter
mismatch for safepoints and we can just tail-call to %GrowArrayElements
from the GrowArrayElementsStub.

Bug: chromium:608675, v8:5269, v8:6408
Change-Id: I1b11d7d00cad02749a0ebc0a7de5e608de6d91c9
Reviewed-on: https://chromium-review.googlesource.com/778861Reviewed-by: Daniel Clifford <danno@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49474}

src/code-stubs.cc

@@ -722,16 +722,7 @@ TF_STUB(GrowArrayElementsStub, CodeStubAssembler) {
   Return(new_elements);
 
   BIND(&runtime);
-  // TODO(danno): Make this a tail call when the stub is only used from TurboFan
-  // code. This musn't be a tail call for now, since the caller site in lithium
-  // creates a safepoint. This safepoint musn't have a different number of
-  // arguments on the stack in the case that a GC happens from the slow-case
-  // allocation path (zero, since all the stubs inputs are in registers) and
-  // when the call happens (it would be two in the tail call case due to the
-  // tail call pushing the arguments on the stack for the runtime call). By not
-  // tail-calling, the runtime call case also has zero arguments on the stack
-  // for the stub frame.
-  Return(CallRuntime(Runtime::kGrowArrayElements, context, object, key));
+  TailCallRuntime(Runtime::kGrowArrayElements, context, object, key);
 }
 
 ArrayConstructorStub::ArrayConstructorStub(Isolate* isolate)