[csa] Make FastCheck actually fast :-)

Mark the not_ok case as deferred.

Bug: v8:8834
Change-Id: I17536e45fb6aa309347b8faaf5f25fb3bbfbf6cf
Reviewed-on: https://chromium-review.googlesource.com/c/1485973Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59830}

src/code-stub-assembler.cc

@@ -150,10 +150,13 @@ void CodeStubAssembler::Check(const NodeGenerator& condition_body,
 }
 
 void CodeStubAssembler::FastCheck(TNode<BoolT> condition) {
-  Label ok(this);
-  GotoIf(condition, &ok);
-  DebugBreak();
-  Goto(&ok);
+  Label ok(this), not_ok(this, Label::kDeferred);
+  Branch(condition, &ok, &not_ok);
+  BIND(&not_ok);
+  {
+    DebugBreak();
+    Goto(&ok);
+  }
   BIND(&ok);
 }