Print PID and isolate address in gc traces.

src/utils.cc

Index: src/utils.cc
diff --git a/src/utils.cc b/src/utils.cc
index c6fe55b5c65d309c190ff3bd3568247c5dc7774f..03f639d514c2db245f0f826321cfdb396e54da50 100644
--- a/src/utils.cc
+++ b/src/utils.cc
@@ -114,6 +114,15 @@ void PrintPID(const char* format, ...) {
 }
 
 
+void PrintIsolate(void* isolate, const char* format, ...) {
+  base::OS::Print("[%d:%p] ", base::OS::GetCurrentProcessId(), isolate);
+  va_list arguments;
+  va_start(arguments, format);
+  base::OS::VPrint(format, arguments);
+  va_end(arguments);
+}
+
+
 int SNPrintF(Vector<char> str, const char* format, ...) {
   va_list args;
   va_start(args, format);