[heap] Fix GC stats with lazy source positions.

In RecordVirtualBytecodeArrayDetails() check whether the BytecodeArray
has a source position table before accessing it, otherwise it will just
crash with --enable-lazy-source-positions.

Bug: v8:8510
Change-Id: I1250e89faf836a8d5976ca98c14b6b7314bacb98
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1559730
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Auto-Submit: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60692}

src/heap/object-stats.cc

@@ -966,8 +966,10 @@ void ObjectStatsCollectorImpl::RecordVirtualBytecodeArrayDetails(
   RecordSimpleVirtualObjectStats(
       bytecode, bytecode->handler_table(),
       ObjectStats::BYTECODE_ARRAY_HANDLER_TABLE_TYPE);
-  RecordSimpleVirtualObjectStats(bytecode, bytecode->SourcePositionTable(),
-                                 ObjectStats::SOURCE_POSITION_TABLE_TYPE);
+  if (bytecode->HasSourcePositionTable()) {
+    RecordSimpleVirtualObjectStats(bytecode, bytecode->SourcePositionTable(),
+                                   ObjectStats::SOURCE_POSITION_TABLE_TYPE);
+  }
 }
 
 namespace {