[error] Add use counters for non-standard Error features

V8 provides non-standard Error API through:

Error.captureStackTrace
Error.prepareStackTrace
Error.stackTraceLimit

Let's add use counters to gauge how wide-spread these are used.

This is the V8 side of required changes.
The Chromium-side CL: https://crrev.com/c/753446

Bug: v8:6975
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: I917cd6344a01670799f6cbf88a4bfff8e8d0d6ad
Reviewed-on: https://chromium-review.googlesource.com/753443Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49113}

include/v8.h

@@ -7074,9 +7074,13 @@ class V8_EXPORT Isolate {
     kLabeledExpressionStatement = 40,
     kLineOrParagraphSeparatorAsLineTerminator = 41,
     kIndexAccessor = 42,
+    kErrorCaptureStackTrace = 43,
+    kErrorPrepareStackTrace = 44,
+    kErrorStackTraceLimit = 45,
 
     // If you add new values here, you'll also need to update Chromium's:
-    // UseCounter.h, V8PerIsolateData.cpp, histograms.xml
+    // web_feature.mojom, UseCounterCallback.cpp, and enums.xml. V8 changes to
+    // this list need to be landed first, then changes on the Chromium side.
     kUseCounterFeatureCount  // This enum value must be last.
   };
 

src/builtins/builtins-error.cc

@@ -42,6 +42,8 @@ BUILTIN(ErrorCaptureStackTrace) {
   HandleScope scope(isolate);
   Handle<Object> object_obj = args.atOrUndefined(isolate, 1);
 
+  isolate->CountUsage(v8::Isolate::kErrorCaptureStackTrace);
+
   if (!object_obj->IsJSObject()) {
     THROW_NEW_ERROR_RETURN_FAILURE(
         isolate, NewTypeError(MessageTemplate::kInvalidArgument, object_obj));

src/isolate.cc

@@ -568,6 +568,11 @@ bool GetStackTraceLimit(Isolate* isolate, int* result) {
 
   // Ensure that limit is not negative.
   *result = Max(FastD2IChecked(stack_trace_limit->Number()), 0);
+
+  if (*result != FLAG_stack_trace_limit) {
+    isolate->CountUsage(v8::Isolate::kErrorStackTraceLimit);
+  }
+
   return true;
 }
 

src/messages.cc

@@ -952,6 +952,8 @@ MaybeHandle<Object> ErrorUtils::FormatStackTrace(Isolate* isolate,
   if (prepare_stack_trace->IsJSFunction() && !in_recursion) {
     PrepareStackTraceScope scope(isolate);
 
+    isolate->CountUsage(v8::Isolate::kErrorPrepareStackTrace);
+
     Handle<JSArray> sites;
     ASSIGN_RETURN_ON_EXCEPTION(isolate, sites, GetStackFrames(isolate, elems),
                                Object);