Revert of [turbofan] Extend escape analysis to reduce certain CheckMaps....

Revert of [turbofan] Extend escape analysis to reduce certain CheckMaps. (patchset #1 id:1 of https://codereview.chromium.org/2964473002/ )

Reason for revert:
Speculative revert for tiny fire on Canary (crbug.com/738781)

Original issue's description:
> [turbofan] Extend escape analysis to reduce certain CheckMaps.
>
> Enable the experimental support in escape analysis to deal with
> constant-foldable CheckMaps nodes and remove them from the effect
> chain w/o blocking the scalar replacement of the object.
>
> BUG=v8:4586,v8:5267
> R=tebbi@chromium.org
>
> Review-Url: https://codereview.chromium.org/2964473002
> Cr-Commit-Position: refs/heads/master@{#46311}
> Committed: https://chromium.googlesource.com/v8/v8/+/adf7f54e24c4b31207b4df0e30c28f7579b18f5c

TBR=tebbi@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=v8:4586,v8:5267

Review-Url: https://codereview.chromium.org/2970663002
Cr-Commit-Position: refs/heads/master@{#46372}

src/compiler/escape-analysis.cc

@@ -1517,30 +1517,33 @@ void EscapeAnalysis::ProcessCheckMaps(Node* node) {
   DCHECK_EQ(node->opcode(), IrOpcode::kCheckMaps);
   ForwardVirtualState(node);
   Node* checked = ResolveReplacement(NodeProperties::GetValueInput(node, 0));
-  VirtualState* state = virtual_states_[node->id()];
-  if (VirtualObject* object = GetVirtualObject(state, checked)) {
-    if (!object->IsTracked()) {
-      if (status_analysis_->SetEscaped(node)) {
-        TRACE(
-            "Setting #%d (%s) to escaped because checked object #%i is not "
-            "tracked\n",
-            node->id(), node->op()->mnemonic(), object->id());
+  if (FLAG_turbo_experimental) {
+    VirtualState* state = virtual_states_[node->id()];
+    if (VirtualObject* object = GetVirtualObject(state, checked)) {
+      if (!object->IsTracked()) {
+        if (status_analysis_->SetEscaped(node)) {
+          TRACE(
+              "Setting #%d (%s) to escaped because checked object #%i is not "
+              "tracked\n",
+              node->id(), node->op()->mnemonic(), object->id());
+        }
+        return;
       }
-      return;
-    }
-    CheckMapsParameters params = CheckMapsParametersOf(node->op());
+      CheckMapsParameters params = CheckMapsParametersOf(node->op());
 
-    Node* value = object->GetField(HeapObject::kMapOffset / kPointerSize);
-    if (value) {
-      value = ResolveReplacement(value);
-      // TODO(tebbi): We want to extend this beyond constant folding with a
-      // CheckMapsValue operator that takes the load-eliminated map value as
-      // input.
-      if (value->opcode() == IrOpcode::kHeapConstant &&
-          params.maps().contains(ZoneHandleSet<Map>(
-              Handle<Map>::cast(OpParameter<Handle<HeapObject>>(value))))) {
-        TRACE("CheckMaps #%i seems to be redundant (until now).\n", node->id());
-        return;
+      Node* value = object->GetField(HeapObject::kMapOffset / kPointerSize);
+      if (value) {
+        value = ResolveReplacement(value);
+        // TODO(tebbi): We want to extend this beyond constant folding with a
+        // CheckMapsValue operator that takes the load-eliminated map value as
+        // input.
+        if (value->opcode() == IrOpcode::kHeapConstant &&
+            params.maps().contains(ZoneHandleSet<Map>(
+                Handle<Map>::cast(OpParameter<Handle<HeapObject>>(value))))) {
+          TRACE("CheckMaps #%i seems to be redundant (until now).\n",
+                node->id());
+          return;
+        }
       }
     }
   }