Change wordBoundary to take dynamic temporarily (flutter#13765)

Converting the argument to Paragraph.wordBoundary to dynamic temporarily until the framework code is converted to send a TextPosition instead of an int.

I'll submit this, then update the framework side to send a TextPosition, and expect a TextRange
or a List<int>, and then submit that, then I'll change this code to send a TextRange and take a TextPostion only, removing the dynamic here. Once that's done, I'll remove the code in the framework that expects a TextRange or a List<int>, and have it just expect a TextRange.

This is so that we can change the API without breaking the builds.

Landing on red to kick the engine builds.

Author: gspencergoog

lib/ui/text.dart

@@ -1871,7 +1871,17 @@ class Paragraph extends NativeFieldWrapperClass2 {
   /// on both sides. In such cases, this method will return [offset, offset+1].
   /// Word boundaries are defined more precisely in Unicode Standard Annex #29
   /// http://www.unicode.org/reports/tr29/#Word_Boundaries
-  List<int> getWordBoundary(int offset) native 'Paragraph_getWordBoundary';
+  List<int> getWordBoundary(dynamic position) {
+    // TODO(gspencergoog): have this take only a TextPosition once the framework
+    // code is calling it with that.
+    if (position is TextPosition) {
+      return _getWordBoundary(position.offset);
+    } else {
+      final int offset = position;
+      return _getWordBoundary(offset);
+    }
+  }
+  List<int> _getWordBoundary(int offset) native 'Paragraph_getWordBoundary';
 
   // Redirecting the paint function in this way solves some dependency problems
   // in the C++ code. If we straighten out the C++ dependencies, we can remove

lib/web_ui/lib/src/engine/text/paragraph.dart

@@ -281,13 +281,26 @@ class EngineParagraph implements ui.Paragraph {
   }
 
   @override
-  List<int> getWordBoundary(int offset) {
+  List<int> getWordBoundary(dynamic position) {
+    // TODO(gspencergoog): have this take only a TextPosition once the framework
+    // code is calling it with that.
+    if (position is ui.TextPosition) {
+      ui.TextPosition textPosition = position;
+      if (_plainText == null) {
+        return <int>[textPosition.offset, textPosition.offset];
+      }
+
+      final int start = WordBreaker.prevBreakIndex(_plainText, textPosition.offset);
+      final int end = WordBreaker.nextBreakIndex(_plainText, textPosition.offset);
+      return <int>[start, end];
+    }
+
     if (_plainText == null) {
-      return <int>[offset, offset];
+      return <int>[position, position];
     }
 
-    final int start = WordBreaker.prevBreakIndex(_plainText, offset);
-    final int end = WordBreaker.nextBreakIndex(_plainText, offset);
+    final int start = WordBreaker.prevBreakIndex(_plainText, position);
+    final int end = WordBreaker.nextBreakIndex(_plainText, position);
     return <int>[start, end];
   }
 

lib/web_ui/lib/src/ui/text.dart

@@ -1242,7 +1242,7 @@ abstract class Paragraph {
   /// on both sides. In such cases, this method will return [offset, offset+1].
   /// Word boundaries are defined more precisely in Unicode Standard Annex #29
   /// http://www.unicode.org/reports/tr29/#Word_Boundaries
-  List<int> getWordBoundary(int offset);
+  List<int> getWordBoundary(dynamic position);
 
   /// Returns a list of text boxes that enclose all placeholders in the paragraph.
   ///