Refactor Isolate name format, storage and log

runtime/vm/dart_api_impl.cc

Index: runtime/vm/dart_api_impl.cc
diff --git a/runtime/vm/dart_api_impl.cc b/runtime/vm/dart_api_impl.cc
index 6347cc98683a3a15975e4e051052af1ef25d2366..17d4ed6e814d0fa2a81b258ca142afc0e657f63f 100644
--- a/runtime/vm/dart_api_impl.cc
+++ b/runtime/vm/dart_api_impl.cc
@@ -1096,9 +1096,9 @@ static char* BuildIsolateName(const char* script_uri, const char* main) {
   }
 
   char* chars = NULL;
-  intptr_t len = OS::SNPrint(NULL, 0, "%s$%s", script_uri, main) + 1;
+  intptr_t len = OS::SNPrint(NULL, 0, "%s:%s()", script_uri, main) + 1;
   chars = reinterpret_cast<char*>(malloc(len));
-  OS::SNPrint(chars, len, "%s$%s", script_uri, main);
+  OS::SNPrint(chars, len, "%s:%s()", script_uri, main);
   return chars;
 }