Expose a lower bound of malloc'd memory via heap statistics

src/crankshaft/compilation-phase.cc

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/crankshaft/compilation-phase.h"
 
 #include "src/crankshaft/hydrogen.h"
 #include "src/isolate.h"
 
 namespace v8 {
 namespace internal {
 
 CompilationPhase::CompilationPhase(const char* name, CompilationInfo* info)
-    : name_(name), info_(info) {
+    : name_(name), info_(info), zone_(info->isolate()->allocator()) {
   if (FLAG_hydrogen_stats) {
     info_zone_start_allocation_size_ = info->zone()->allocation_size();
     timer_.Start();
   }
 }
 
 CompilationPhase::~CompilationPhase() {
   if (FLAG_hydrogen_stats) {
     size_t size = zone()->allocation_size();
     size += info_->zone()->allocation_size() - info_zone_start_allocation_size_;
@@ skipping 10 matching lines @@
           ? FLAG_trace_hydrogen_stubs
           : (FLAG_trace_hydrogen &&
              info()->shared_info()->PassesFilter(FLAG_trace_hydrogen_filter));
   return (tracing_on &&
           base::OS::StrChr(const_cast<char*>(FLAG_trace_phase), name_[0]) !=
               NULL);
 }
 
 }  // namespace internal
 }  // namespace v8