Add flags to force or prevent setting of isolate.is_memory_constrained.

src/isolate.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1758 matching lines @@
       thread_manager_(NULL),
       fp_stubs_generated_(false),
       has_installed_extensions_(false),
       string_tracker_(NULL),
       regexp_stack_(NULL),
       date_cache_(NULL),
       code_stub_interface_descriptors_(NULL),
       // TODO(bmeurer) Initialized lazily because it depends on flags; can
       // be fixed once the default isolate cleanup is done.
       random_number_generator_(NULL),
+      // TODO(rmcilroy) Currently setting this based on
+      // FLAG_force_memory_constrained in Isolate::Init; move to here when
+      // isolate cleanup is done
       is_memory_constrained_(false),
       has_fatal_error_(false),
       use_crankshaft_(true),
       initialized_from_snapshot_(false),
       cpu_profiler_(NULL),
       heap_profiler_(NULL),
       function_entry_hook_(NULL),
       deferred_handles_head_(NULL),
       optimizing_compiler_thread_(this),
       marking_thread_(NULL),
@@ skipping 339 matching lines @@
   Release_Store(&debugger_initialized_, true);
 #endif
 }
 
 
 bool Isolate::Init(Deserializer* des) {
   ASSERT(state_ != INITIALIZED);
   TRACE_ISOLATE(init);
 
   stress_deopt_count_ = FLAG_deopt_every_n_times;
+  if (FLAG_force_memory_constrained.has_value)
+    is_memory_constrained_ = FLAG_force_memory_constrained.value;
 
   has_fatal_error_ = false;
 
   use_crankshaft_ = FLAG_crankshaft
       && !Serializer::enabled()
       && CPU::SupportsCrankshaft();
 
   if (function_entry_hook() != NULL) {
     // When function entry hooking is in effect, we have to create the code
     // stubs from scratch to get entry hooks, rather than loading the previously
@@ skipping 373 matching lines @@
 
 #ifdef DEBUG
 #define ISOLATE_FIELD_OFFSET(type, name, ignored)                       \
 const intptr_t Isolate::name##_debug_offset_ = OFFSET_OF(Isolate, name##_);
 ISOLATE_INIT_LIST(ISOLATE_FIELD_OFFSET)
 ISOLATE_INIT_ARRAY_LIST(ISOLATE_FIELD_OFFSET)
 #undef ISOLATE_FIELD_OFFSET
 #endif
 
 } }  // namespace v8::internal