Start adding implementations for runtime-provided native methods.

The library can't do everything...

Change-Id: Ib808c00570c7214aeb2ca058b1a66cacbeb372f1
diff --git a/src/heap.cc b/src/heap.cc
index bffd19d..58588ef 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -251,6 +251,21 @@
   return NULL;
 }
 
+int64_t Heap::GetMaxMemory() {
+  UNIMPLEMENTED(WARNING);
+  return 0;
+}
+
+int64_t Heap::GetTotalMemory() {
+  UNIMPLEMENTED(WARNING);
+  return 0;
+}
+
+int64_t Heap::GetFreeMemory() {
+  UNIMPLEMENTED(WARNING);
+  return 0;
+}
+
 void Heap::CollectGarbage() {
   CollectGarbageInternal();
 }