PDF: Prevent a NOTREACHED() in HandleUpdateScrollMessage().

In OutOfProcessInstance::HandleUpdateScrollMessage(), the messages
received from JS sometimes contain integers and sometimes contain
doubles. As such, check validate them with is_number() rather than
is_int().

Bug: 1136983
Change-Id: Id3112e660a96d596b9da92c453caa5f697e5a5f6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2466514Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816405}

pdf/out_of_process_instance.cc

@@ -1852,8 +1852,8 @@ void OutOfProcessInstance::HandleSetTwoUpViewMessage(
 void OutOfProcessInstance::HandleUpdateScrollMessage(
     const pp::VarDictionary& dict) {
   if (!base::FeatureList::IsEnabled(features::kPDFViewerUpdate) ||
-      !dict.Get(pp::Var(kJSUpdateScrollX)).is_int() ||
-      !dict.Get(pp::Var(kJSUpdateScrollY)).is_int()) {
+      !dict.Get(pp::Var(kJSUpdateScrollX)).is_number() ||
+      !dict.Get(pp::Var(kJSUpdateScrollY)).is_number()) {
     NOTREACHED();
     return;
   }