Disable concurrent marking/sweeping, and background compilation on ARMv5TE

runtime/vm/gc_marker.cc

Index: runtime/vm/gc_marker.cc
diff --git a/runtime/vm/gc_marker.cc b/runtime/vm/gc_marker.cc
index cc5db20ce64187a265ec23cd2ad5d2cd8b2ecf5e..2c2643ec8295fa2778a28acc90f3af0c5ba7c41e 100644
--- a/runtime/vm/gc_marker.cc
+++ b/runtime/vm/gc_marker.cc
@@ -25,12 +25,6 @@
 
 namespace dart {
 
-DEFINE_FLAG(int, marker_tasks, 2,
-            "The number of tasks to spawn during old gen GC marking (0 means "
-            "perform all marking on main thread).");
-DEFINE_FLAG(bool, log_marker_tasks, false,
-            "Log debugging information for old gen GC marking tasks.");
-
 class DelaySet {
  private:
   typedef std::multimap<RawObject*, RawWeakProperty*> Map;