[turbofan] reenable escape analysis to further investigate crashes

R=jarin@chromium.org

BUG=chromium:669242

Review-Url: https://codereview.chromium.org/2589163002
Cr-Commit-Position: refs/heads/master@{#41857}

src/compiler/escape-analysis.cc

@@ -441,6 +441,15 @@ bool VirtualObject::MergeFields(size_t i, Node* at, MergeCache* cache,
   Node* rep = GetField(i);
   if (!rep || !IsCreatedPhi(i)) {
     Node* control = NodeProperties::GetControlInput(at);
+
+    // Check to debug canary.
+    CHECK_NOT_NULL(control);
+    CHECK(!control->IsDead());
+    for (Node* input : cache->fields()) {
+      CHECK_NOT_NULL(input);
+      CHECK(!input->IsDead());
+    }
+
     cache->fields().push_back(control);
     Node* phi = graph->NewNode(
         common->Phi(MachineRepresentation::kTagged, value_input_count),

src/flag-definitions.h

@@ -468,8 +468,7 @@ DEFINE_BOOL(turbo_loop_peeling, true, "Turbofan loop peeling")
 DEFINE_BOOL(turbo_loop_variable, true, "Turbofan loop variable optimization")
 DEFINE_BOOL(turbo_cf_optimization, true, "optimize control flow in TurboFan")
 DEFINE_BOOL(turbo_frame_elision, true, "elide frames in TurboFan")
-DEFINE_BOOL(turbo_escape, false, "enable escape analysis")
-DEFINE_IMPLICATION(turbo, turbo_escape)
+DEFINE_BOOL(turbo_escape, true, "enable escape analysis")
 DEFINE_BOOL(turbo_instruction_scheduling, false,
             "enable instruction scheduling in TurboFan")
 DEFINE_BOOL(turbo_stress_instruction_scheduling, false,