Stop creating VisiblePosition in ColdModeSpellCheckRequester

The class creates VisiblePosition to be passed to EndOfSentence(), but
EndOfSentence() doesn't require input position to be canonical.
ColdModeSpellCheckRequester doesn't require the EndOfSentence() output
to be canonical, either.

Hence, this patch changes ColdModeSpellCheckRequester to use the non-
canonical variant of EndOfSentence().

Bug: 657237
Change-Id: I96df36bb49c150f12ba037729221b8bcdaa9c09a
Reviewed-on: https://chromium-review.googlesource.com/c/1298482Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#603139}

third_party/blink/renderer/core/editing/spellcheck/cold_mode_spell_check_requester.cc

@@ -153,8 +153,7 @@ void ColdModeSpellCheckRequester::RequestCheckingForNextChunk() {
   // Chromium spellchecker requires complete sentences to be checked. However,
   // EndOfSentence() sometimes returns null or out-of-editable positions, which
   // are corrected here.
-  const Position extended_end =
-      EndOfSentence(CreateVisiblePosition(chunk_end)).DeepEquivalent();
+  const Position extended_end = EndOfSentence(chunk_end).GetPosition();
   const Position check_end =
       extended_end.IsNull() || extended_end < chunk_end
           ? chunk_end

third_party/blink/renderer/core/editing/visible_units.h

@@ -140,6 +140,9 @@ CORE_EXPORT VisiblePosition NextWordPosition(const VisiblePosition&);
 CORE_EXPORT VisiblePosition StartOfSentence(const VisiblePosition&);
 CORE_EXPORT VisiblePositionInFlatTree
 StartOfSentence(const VisiblePositionInFlatTree&);
+CORE_EXPORT PositionWithAffinity EndOfSentence(const Position&);
+CORE_EXPORT PositionInFlatTreeWithAffinity
+EndOfSentence(const PositionInFlatTree&);
 CORE_EXPORT VisiblePosition EndOfSentence(const VisiblePosition&);
 CORE_EXPORT VisiblePositionInFlatTree
 EndOfSentence(const VisiblePositionInFlatTree&);