Remove default heap size limit and add separate limit for externals.

runtime/vm/dart.cc

Index: runtime/vm/dart.cc
===================================================================
--- runtime/vm/dart.cc	(revision 43108)
+++ runtime/vm/dart.cc	(working copy)
@@ -34,10 +34,14 @@
 
 DEFINE_FLAG(int, new_gen_semi_max_size, (kWordSize <= 4) ? 16 : 32,
             "Max size of new gen semi space in MB");
-DEFINE_FLAG(int, old_gen_heap_size, Heap::kHeapSizeInMB,
-            "Max size of old gen heap size in MB,"
+DEFINE_FLAG(int, old_gen_heap_size, 0,
+            "Max size of old gen heap size in MB, or 0 for unlimited,"
             "e.g: --old_gen_heap_size=1024 allows up to 1024MB old gen heap");
+DEFINE_FLAG(int, external_max_size, (kWordSize <= 4) ? 512 : 1024,
+            "Max total size of external allocations in MB, or 0 for unlimited,"
+            "e.g: --external_max_size=1024 allows up to 1024MB of externals");
 
+
 DECLARE_FLAG(bool, print_class_table);
 DECLARE_FLAG(bool, trace_isolates);
 
@@ -114,7 +118,8 @@
     HandleScope handle_scope(vm_isolate_);
     Heap::Init(vm_isolate_,
                0,  // New gen size 0; VM isolate should only allocate in old.
-               FLAG_old_gen_heap_size * MBInWords);
+               FLAG_old_gen_heap_size * MBInWords,
+               FLAG_external_max_size * MBInWords);
     ObjectStore::Init(vm_isolate_);
     TargetCPUFeatures::InitOnce();
     Object::InitOnce(vm_isolate_);
@@ -197,7 +202,8 @@
   HandleScope handle_scope(isolate);
   Heap::Init(isolate,
              FLAG_new_gen_semi_max_size * MBInWords,
-             FLAG_old_gen_heap_size * MBInWords);
+             FLAG_old_gen_heap_size * MBInWords,
+             FLAG_external_max_size * MBInWords);
   ObjectIdRing::Init(isolate);
   ObjectStore::Init(isolate);