Re-enable Dart_Api Timeline tracing

runtime/vm/dart_api_impl.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "include/dart_api.h"
 #include "include/dart_mirrors_api.h"
 #include "include/dart_native_api.h"
 
 #include "platform/assert.h"
 #include "vm/class_finalizer.h"
@@ skipping 59 matching lines @@
 
 
 const char* CanonicalFunction(const char* func) {
   if (strncmp(func, "dart::", 6) == 0) {
     return func + 6;
   } else {
     return func;
   }
 }
 
-#if 0
 #define API_TIMELINE_DURATION                                                  \
   TimelineDurationScope tds(Thread::Current(),                                 \
                             Timeline::GetVMApiStream(),                        \
                             CURRENT_FUNC)
 
 #define API_TIMELINE_BEGIN_END                                                 \
   TimelineBeginEndScope tbes(Thread::Current(),                                \
                              Timeline::GetVMApiStream(),                       \
                              CURRENT_FUNC)
-#else
-#define API_TIMELINE_DURATION ASSERT(true)
-#define API_TIMELINE_BEGIN_END ASSERT(true)
-#endif
+
 
 #if defined(DEBUG)
 // An object visitor which will iterate over all the function objects in the
 // heap and check if the result type and parameter types are canonicalized
 // or not. An assertion is raised if a type is not canonicalized.
 class FunctionVisitor : public ObjectVisitor {
  public:
   explicit FunctionVisitor(Thread* thread) :
       ObjectVisitor(thread->isolate()),
       classHandle_(Class::Handle(thread->zone())),
@@ skipping 5874 matching lines @@
   return Api::Success();
 }
 #endif  // DART_PRECOMPILED
 
 
 DART_EXPORT bool Dart_IsRunningPrecompiledCode() {
   return Dart::IsRunningPrecompiledCode();
 }
 
 }  // namespace dart