Reimplement Maps and Sets in JS

src/x64/code-stubs-x64.cc

Index: src/x64/code-stubs-x64.cc
diff --git a/src/x64/code-stubs-x64.cc b/src/x64/code-stubs-x64.cc
index 49904297febf74a2e61c0d712fd560c29ffce803..0ca316e536b49d417fb9cdc78b9f6a70f6fbff37 100644
--- a/src/x64/code-stubs-x64.cc
+++ b/src/x64/code-stubs-x64.cc
@@ -2415,16 +2415,6 @@ void CEntryStub::Generate(MacroAssembler* masm) {
   }
 #endif  // _WIN64
 
-  // Runtime functions should not return 'the hole'.  Allowing it to escape may
-  // lead to crashes in the IC code later.
-  if (FLAG_debug_code) {
-    Label okay;
-    __ CompareRoot(rax, Heap::kTheHoleValueRootIndex);
-    __ j(not_equal, &okay, Label::kNear);
-    __ int3();
-    __ bind(&okay);
-  }
-
   // Check result for exception sentinel.
   Label exception_returned;
   __ CompareRoot(rax, Heap::kExceptionRootIndex);