Add --print-benchmarking-metrics to the VM for Golem.

runtime/vm/metrics.h

Index: runtime/vm/metrics.h
diff --git a/runtime/vm/metrics.h b/runtime/vm/metrics.h
index fd4449bcabb241281731b43cdcba31bd9a363ef6..e3d6a36a947f10b1e6d989e6b5b34b1e81942737 100644
--- a/runtime/vm/metrics.h
+++ b/runtime/vm/metrics.h
@@ -25,7 +25,9 @@ class JSONStream;
   V(MaxMetric, HeapNewCapacityMax, "heap.new.capacity.max", kByte)             \
   V(MetricHeapNewExternal, HeapNewExternal, "heap.new.external", kByte)        \
   V(MetricHeapUsed, HeapGlobalUsed, "heap.global.used", kByte)                 \
-  V(MaxMetric, HeapGlobalUsedMax, "heap.global.used.max", kByte)
+  V(MaxMetric, HeapGlobalUsedMax, "heap.global.used.max", kByte)               \
+  V(Metric, RunnableLatency, "isolate.runnable.latency", kMicrosecond)         \
+  V(Metric, RunnableHeapSize, "isolate.runnable.heap", kByte)
 
 #define VM_METRIC_LIST(V)                                                      \
   V(MetricIsolateCount, IsolateCount, "vm.isolate.count", kCounter)
@@ -35,6 +37,7 @@ class Metric {
   enum Unit {
     kCounter,
     kByte,
+    kMicrosecond,
   };
 
   Metric();