Add -optimize-for-size flag to optimize for memory size

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 0a38fa9f32b2b3e3932a178d756c80b44b1a0c1e..fcea10a56b62f8831c719ab8006fdadcdb7f00a6 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -602,8 +602,7 @@ ResourceConstraints::ResourceConstraints()
   : max_young_space_size_(0),
     max_old_space_size_(0),
     max_executable_size_(0),
-    stack_limit_(NULL),
-    is_memory_constrained_() { }
+    stack_limit_(NULL) { }
 
 
 bool SetResourceConstraints(ResourceConstraints* constraints) {
@@ -624,11 +623,6 @@ bool SetResourceConstraints(ResourceConstraints* constraints) {
     uintptr_t limit = reinterpret_cast<uintptr_t>(constraints->stack_limit());
     isolate->stack_guard()->SetStackLimit(limit);
   }
-  if (constraints->is_memory_constrained().has_value &&
-      !i::FLAG_force_memory_constrained.has_value) {
-    isolate->set_is_memory_constrained(
-        constraints->is_memory_constrained().value);
-  }
   return true;
 }