Remove RenderEditable textPainter height hack (#113301)

* remove RenderEditable textPainter height hack

* Still applies the hack on web

* unskip web

Author: LongCatIsLooong

packages/flutter/lib/src/rendering/editable.dart

@@ -1878,21 +1878,10 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
       return math.max(estimatedHeight, minHeight);
     }
 
-    // TODO(LongCatIsLooong): this is a workaround for
-    // https://github.com/flutter/flutter/issues/112123.
-    // Use preferredLineHeight since SkParagraph currently returns an incorrect
-    // height.
-    final TextHeightBehavior? textHeightBehavior = this.textHeightBehavior;
-    final bool usePreferredLineHeightHack = maxLines == 1
-        && text?.codeUnitAt(0) == null
-        && strutStyle != null && strutStyle != StrutStyle.disabled
-        && textHeightBehavior != null
-        && (!textHeightBehavior.applyHeightToFirstAscent || !textHeightBehavior.applyHeightToLastDescent);
-
     // Special case maxLines == 1 since it forces the scrollable direction
     // to be horizontal. Report the real height to prevent the text from being
     // clipped.
-    if (maxLines == 1 && !usePreferredLineHeightHack) {
+    if (maxLines == 1) {
       // The _layoutText call lays out the paragraph using infinite width when
       // maxLines == 1. Also _textPainter.maxLines will be set to 1 so should
       // there be any line breaks only the first line is shown.

packages/flutter/test/painting/text_painter_test.dart

@@ -1217,12 +1217,36 @@ void main() {
       textDirection: TextDirection.ltr,
     );
 
-    textPainter.layout();
-    expect(
-      textPainter.getWordBoundary(const TextPosition(offset: 8)),
-      const TextRange(start: 8, end: 16),
+     textPainter.layout();
+     expect(
+       textPainter.getWordBoundary(const TextPosition(offset: 8)),
+       const TextRange(start: 8, end: 16),
+     );
+   }, skip: isBrowser); // https://github.com/flutter/flutter/issues/61017
+
+  test('TextHeightBehavior with strut on empty paragraph', () {
+    // Regression test for https://github.com/flutter/flutter/issues/112123
+    const TextStyle style = TextStyle(height: 11, fontSize: 7);
+    const TextSpan simple = TextSpan(text: 'x', style: style);
+    const TextSpan emptyString = TextSpan(text: '', style: style);
+    const TextSpan emptyParagraph = TextSpan(style: style);
+
+    final TextPainter painter = TextPainter(
+      textDirection: TextDirection.ltr,
+      strutStyle: StrutStyle.fromTextStyle(style, forceStrutHeight: true),
+      textHeightBehavior: const TextHeightBehavior(applyHeightToFirstAscent: false, applyHeightToLastDescent: false),
     );
-  }, skip: isBrowser); // https://github.com/flutter/flutter/issues/61017
+
+    painter.text = simple;
+    painter.layout();
+    final double height = painter.height;
+    for (final TextSpan span in <TextSpan>[simple, emptyString, emptyParagraph]) {
+      painter.text = span;
+      painter.layout();
+      expect(painter.height, height, reason: '$span is expected to have a height of $height');
+      expect(painter.preferredLineHeight, height, reason: '$span is expected to have a height of $height');
+    }
+  });
 
   test('TextPainter plainText getter', () {
     final TextPainter painter = TextPainter()