Fix join for traces without symbols.

Change-Id: I63de941b3560e7c18fb9433358d576bcb2ae333e
diff --git a/ui/src/controller/heap_profile_controller.ts b/ui/src/controller/heap_profile_controller.ts
index a556b92..973a92f 100644
--- a/ui/src/controller/heap_profile_controller.ts
+++ b/ui/src/controller/heap_profile_controller.ts
@@ -256,7 +256,7 @@
          from stack_profile_callsite cs
          join stack_profile_frame fr on cs.frame_id = fr.id
          join stack_profile_mapping map on fr.mapping = map.id
-         inner join (
+         left join (
               select symbol_set_id, FIRST_VALUE(name) OVER(PARTITION BY
                 symbol_set_id) as name
               from stack_profile_symbol GROUP BY symbol_set_id