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 d4b97b3cb36334eceff242bc509f8fd0b417e404..36f2fcfdf23d3b14d3b73cfa8a3c74305b23925f 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;
@@ -1162,6 +1163,10 @@ 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);
@@ -1389,6 +1394,8 @@ class Isolate {
 
   interpreter::Interpreter* interpreter_;
 
+  CompilerDispatcherTracer* compiler_dispatcher_tracer_;
+
   typedef std::pair<InterruptCallback, void*> InterruptEntry;
   std::queue<InterruptEntry> api_interrupts_queue_;