[inspector] Reduce upper bound for async stack traces.

The V8Debugger maintains a list of async stack traces that were captured
so far, two mappings pointing weakly to async stack traces in this (one
mapping for tasks and one mapping for stored async stack traces). The
V8Debugger regularly prunes the list (and cleans up the stale weak
pointers afterwards) by going through the list in insertion order and
removing items until the number is below half the limit of 128k entries.

This approach wastes a lot of memory, since the list grows very big
before this manual collection starts, and it doesn't pay any attention
to whether the stack traces are still in active use or not. Also the
limit of 128k seems incredibly high (and arbitrary).

This leads to crashes observed in applications with lots of async task
activity (i.e. huge Angular applications) as soon as the debugger is
attached.

This CL performs a quickfix by reducing the limit for async stack traces
to a more reasonable number of 8k. We will need to follow up with a
proper fix that ensures that we only hold on strongly to async stack
traces that are still in need.

Also-By: jarin@chromium.org
Fixed: chromium:1258000
Bug: chromium:1257637, chromium:1254279, chromium:1203218
Change-Id: I2c482a688df4c6df575a0045d443db89d89b3d73
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3211709
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Auto-Submit: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77301}

src/inspector/v8-debugger.cc

@@ -23,7 +23,7 @@ namespace v8_inspector {
 
 namespace {
 
-static const int kMaxAsyncTaskStacks = 128 * 1024;
+static const int kMaxAsyncTaskStacks = 8 * 1024;
 static const int kNoBreakpointId = 0;
 
 template <typename Map>