Make GDBJIT interface compile again.

src/mark-compact.cc

Index: src/mark-compact.cc
diff --git a/src/mark-compact.cc b/src/mark-compact.cc
index 2704f51f0adf83ed3d90a1de4dcb14ce0e189c4a..dd34ea31309cd66c92008b04115cd808eeed57f0 100644
--- a/src/mark-compact.cc
+++ b/src/mark-compact.cc
@@ -339,6 +339,11 @@ bool MarkCompactCollector::StartCompaction(CompactionMode mode) {
   if (!compacting_) {
     ASSERT(evacuation_candidates_.length() == 0);
 
+#ifdef ENABLE_GDB_JIT_INTERFACE
+    // If GDBJIT interface is active disable compaction.
+    if (FLAG_gdbjit) return false;
+#endif
+
     CollectEvacuationCandidates(heap()->old_pointer_space());
     CollectEvacuationCandidates(heap()->old_data_space());
 
@@ -778,13 +783,6 @@ void MarkCompactCollector::Prepare(GCTracer* tracer) {
 
   ASSERT(!FLAG_never_compact || !FLAG_always_compact);
 
-#ifdef ENABLE_GDB_JIT_INTERFACE
-  if (FLAG_gdbjit) {
-    // If GDBJIT interface is active disable compaction.
-    compacting_collection_ = false;
-  }
-#endif
-
   // Clear marking bits if incremental marking is aborted.
   if (was_marked_incrementally_ && abort_incremental_marking_) {
     heap()->incremental_marking()->Abort();