Fixed compilation time measurement, restructure some code.

runtime/vm/timer.h

Index: runtime/vm/timer.h
===================================================================
--- runtime/vm/timer.h	(revision 7417)
+++ runtime/vm/timer.h	(working copy)
@@ -38,16 +38,24 @@
     }
   }
 
-  // Get total cummulative elapsed time in micros and reset the counters.
-  int64_t TotalElapsedTime() {
+  // Get total cummulative elapsed time in micros.
+  int64_t TotalElapsedTime() const {
     if (enabled_) {
       int64_t result = total_;
-      Reset();
       return result;
     }
     return 0;
   }
 
+  void Reset() {
+    if (enabled_) {
+      start_ = 0;
+      stop_ = 0;
+      total_ = 0;
+      running_ = false;
+    }
+  }
+
   // Accessors.
   bool enabled() const { return enabled_; }
   bool running() const { return running_; }
@@ -63,15 +71,6 @@
     return 0;
   }
 
-  void Reset() {
-    if (enabled_) {
-      start_ = 0;
-      stop_ = 0;
-      total_ = 0;
-      running_ = false;
-    }
-  }
-
   int64_t start_;
   int64_t stop_;
   int64_t total_;
@@ -140,10 +139,10 @@
 //   code that needs to be timed.
 //   ....
 // }
-class TimerScope : public ValueObject {
+class TimerScope : public StackResource {
  public:
-  TimerScope(bool flag, Timer* timer)
-      : flag_(flag), nested_(false), timer_(timer) {
+  TimerScope(bool flag, Timer* timer, BaseIsolate* isolate = NULL)
+      : StackResource(isolate), flag_(flag), nested_(false), timer_(timer) {
     if (flag_) {
       if (!timer_->running()) {
         timer_->Start();