[wasm][eh] Add histogram for uncaught exceptions

R=ahaas@chromium.org

Bug: v8:8091
Change-Id: Id539bc96d9c791e3ed89d822189ab804ea9a24ea
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2699260Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72843}

src/logging/counters-definitions.h

@@ -91,6 +91,8 @@ namespace internal {
   HR(wasm_rethrow_count, V8.WasmReThrowCount, 0, 100000, 30)                   \
   /* number of caught exceptions per isolate */                                \
   HR(wasm_catch_count, V8.WasmCatchCount, 0, 100000, 30)                       \
+  /* number of uncaught exceptions per isolate */                              \
+  HR(wasm_uncaught_count, V8.WasmUncaughtCount, 0, 100000, 30)                 \
   /* Ticks observed in a single Turbofan compilation, in 1K */                 \
   HR(turbofan_ticks, V8.TurboFan1KTicks, 0, 100000, 200)                       \
   /* Backtracks observed in a single regexp interpreter execution */           \

src/wasm/wasm-engine.cc

@@ -1019,6 +1019,8 @@ void WasmEngine::RemoveIsolate(Isolate* isolate) {
   isolate->counters()->wasm_throw_count()->AddSample(info->throw_count);
   isolate->counters()->wasm_rethrow_count()->AddSample(info->rethrow_count);
   isolate->counters()->wasm_catch_count()->AddSample(info->catch_count);
+  isolate->counters()->wasm_uncaught_count()->AddSample(
+      info->throw_count + info->rethrow_count - info->catch_count);
 }
 
 void WasmEngine::LogCode(Vector<WasmCode*> code_vec) {