[crankshaft] Protect against deopt loops from string length overflows.

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index 02e0877117e87678938a67f307cbc7daeec53864..cf319454d39ea1ef53b0fa9cd8c3d5331883ac1f 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -2818,6 +2818,15 @@ void Isolate::InvalidateArraySpeciesProtector() {
   DCHECK(!IsArraySpeciesLookupChainIntact());
 }
 
+void Isolate::InvalidateStringLengthOverflowProtector() {
+  DCHECK(factory()->string_length_protector()->value()->IsSmi());
+  DCHECK(IsStringLengthOverflowIntact());
+  PropertyCell::SetValueWithInvalidation(
+      factory()->string_length_protector(),
+      handle(Smi::FromInt(kArrayProtectorInvalid), this));
+  DCHECK(!IsStringLengthOverflowIntact());
+}
+
 bool Isolate::IsAnyInitialArrayPrototype(Handle<JSArray> array) {
   DisallowHeapAllocation no_gc;
   return IsInAnyContext(*array, Context::INITIAL_ARRAY_PROTOTYPE_INDEX);