Introduce a CompilerDispatcherTracer and track how long jobs take

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index 7c29880abcd96c315a3eb31dc362c2ad4f8860ac..d7f0f206155beeb2e75569b6711ae5fd04744c81 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -45,6 +45,7 @@ class CodeRange;
 class CodeStubDescriptor;
 class CodeTracer;
 class CompilationCache;
+class CompilerDispatcherTracer;
 class CompilationStatistics;
 class ContextSlotCache;
 class Counters;
@@ -1159,6 +1160,10 @@ class Isolate {
 
   AccountingAllocator* allocator() { return allocator_; }
 
+  CompilerDispatcherTracer* compiler_dispatcher_tracer() const {
+    return compiler_dispatcher_tracer_;
+  }
+
   bool IsInAnyContext(Object* object, uint32_t index);
 
   void SetRAILMode(RAILMode rail_mode);
@@ -1386,6 +1391,8 @@ class Isolate {
 
   interpreter::Interpreter* interpreter_;
 
+  CompilerDispatcherTracer* compiler_dispatcher_tracer_;
+
   typedef std::pair<InterruptCallback, void*> InterruptEntry;
   std::queue<InterruptEntry> api_interrupts_queue_;