Avoid redundant scans of the instance lists

When the instance lists grow to a sizable length, checking for and
removing instance time with a kScript origin can take significant time
in some cases - especially when there are no such instance times present
at all.
Add a bitmask encoding which origins are present in the list, and then
use that to avoid redundant scans (in RemoveWithOrigin) when possible.

Bug: 1039243
Change-Id: I7008927338508f08e8b416822fbe52073a86da1b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2089706
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#748627}

third_party/blink/renderer/core/svg/animation/svg_smil_element.cc

@@ -67,6 +67,7 @@ SMILTime ComputeNextRepeatTime(SMILTime interval_begin,
 
 void SMILInstanceTimeList::Append(SMILTime time, SMILTimeOrigin origin) {
   instance_times_.push_back(SMILTimeWithOrigin(time, origin));
+  AddOrigin(origin);
 }
 
 void SMILInstanceTimeList::InsertSortedAndUnique(SMILTime time,
@@ -84,15 +85,19 @@ void SMILInstanceTimeList::InsertSortedAndUnique(SMILTime time,
       return;
   }
   instance_times_.insert(position - instance_times_.begin(), time_with_origin);
+  AddOrigin(origin);
 }
 
 void SMILInstanceTimeList::RemoveWithOrigin(SMILTimeOrigin origin) {
+  if (!HasOrigin(origin))
+    return;
   auto* tail =
       std::remove_if(instance_times_.begin(), instance_times_.end(),
                      [origin](const SMILTimeWithOrigin& instance_time) {
                        return instance_time.Origin() == origin;
                      });
   instance_times_.Shrink(tail - instance_times_.begin());
+  ClearOrigin(origin);
 }
 
 void SMILInstanceTimeList::Sort() {

third_party/blink/renderer/core/svg/animation/svg_smil_element.h

@@ -58,7 +58,21 @@ class CORE_EXPORT SMILInstanceTimeList {
   const_iterator end() const { return instance_times_.end(); }
 
  private:
+  static unsigned OriginToMask(SMILTimeOrigin origin) {
+    return 1u << static_cast<unsigned>(origin);
+  }
+  void AddOrigin(SMILTimeOrigin origin) {
+    time_origin_mask_ |= OriginToMask(origin);
+  }
+  void ClearOrigin(SMILTimeOrigin origin) {
+    time_origin_mask_ &= ~OriginToMask(origin);
+  }
+  bool HasOrigin(SMILTimeOrigin origin) const {
+    return (time_origin_mask_ & OriginToMask(origin)) != 0;
+  }
+
   Vector<SMILTimeWithOrigin> instance_times_;
+  unsigned time_origin_mask_ = 0;
 };
 
 // This class implements SMIL interval timing model as needed for SVG animation.