Expose noncanonical versions of Previous/NextWordPosition

This patch exposes noncanonical versions of Previous/NextWordPosition to
reduce usage of VisiblePosition.

Bug: 657237
Change-Id: I0815b0c0bf4de34427432ca8f6aa769c356c6385
Reviewed-on: https://chromium-review.googlesource.com/c/1313876Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Yoichi Osato <yoichio@chromium.org>
Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#604832}

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

@@ -133,7 +133,10 @@ EndOfWordPosition(const VisiblePositionInFlatTree&,
                   EWordSide = kNextWordIfOnBoundary);
 CORE_EXPORT VisiblePositionInFlatTree
 EndOfWord(const VisiblePositionInFlatTree&, EWordSide = kNextWordIfOnBoundary);
+// TODO(crbug.com/657237): Change all callers to use non-canonical versions.
+CORE_EXPORT PositionWithAffinity PreviousWordPosition(const Position&);
 CORE_EXPORT VisiblePosition PreviousWordPosition(const VisiblePosition&);
+CORE_EXPORT PositionWithAffinity NextWordPosition(const Position&);
 CORE_EXPORT VisiblePosition NextWordPosition(const VisiblePosition&);
 
 // sentences

third_party/blink/renderer/core/editing/visible_units_word_test.cc

@@ -33,13 +33,13 @@ class VisibleUnitsWordTest : public EditingTestBase {
   std::string DoNextWord(const std::string& selection_text) {
     const Position position = SetSelectionTextToBody(selection_text).Base();
     return GetCaretTextFromBody(
-        NextWordPosition(CreateVisiblePosition(position)).DeepEquivalent());
+        CreateVisiblePosition(NextWordPosition(position)).DeepEquivalent());
   }
 
   std::string DoPreviousWord(const std::string& selection_text) {
     const Position position = SetSelectionTextToBody(selection_text).Base();
     const Position result =
-        PreviousWordPosition(CreateVisiblePosition(position)).DeepEquivalent();
+        CreateVisiblePosition(PreviousWordPosition(position)).DeepEquivalent();
     if (result.IsNull())
       return GetSelectionTextFromBody(SelectionInDOMTree());
     return GetCaretTextFromBody(result);