Adds leadingDistribution to equality checker in StrutStyle (#164813)

Fixes #164811 
Adds `leadingDistribution` to equality checker.

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- [ ] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
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packages/flutter/lib/src/painting/strut_style.dart

@@ -528,7 +528,8 @@ class StrutStyle with Diagnosticable {
         height != other.height ||
         leading != other.leading ||
         forceStrutHeight != other.forceStrutHeight ||
-        !listEquals(fontFamilyFallback, other.fontFamilyFallback)) {
+        (!listEquals(fontFamilyFallback, other.fontFamilyFallback)) ||
+        (height != null && leadingDistribution != other.leadingDistribution)) {
       return RenderComparison.layout;
     }
     return RenderComparison.identical;
@@ -547,16 +548,20 @@ class StrutStyle with Diagnosticable {
       return this;
     }
 
+    final double? effectiveHeight = height ?? other.height;
+
     return StrutStyle(
       fontFamily: fontFamily ?? other.fontFamily,
       fontFamilyFallback: fontFamilyFallback ?? other.fontFamilyFallback,
       fontSize: fontSize ?? other.fontSize,
-      height: height ?? other.height,
+      height: effectiveHeight,
       leading: leading, // No equivalent property in TextStyle yet.
       fontWeight: fontWeight ?? other.fontWeight,
       fontStyle: fontStyle ?? other.fontStyle,
       forceStrutHeight: forceStrutHeight, // StrutStyle-unique property.
       debugLabel: debugLabel ?? other.debugLabel,
+      leadingDistribution:
+          effectiveHeight != null ? (leadingDistribution ?? other.leadingDistribution) : null,
       // Package is embedded within the getters for fontFamilyFallback.
     );
   }
@@ -576,7 +581,9 @@ class StrutStyle with Diagnosticable {
         other.fontStyle == fontStyle &&
         other.height == height &&
         other.leading == leading &&
-        other.forceStrutHeight == forceStrutHeight;
+        other.forceStrutHeight == forceStrutHeight &&
+        (height == null || leadingDistribution == other.leadingDistribution) &&
+        listEquals(other.fontFamilyFallback, fontFamilyFallback);
   }
 
   @override
@@ -623,6 +630,15 @@ class StrutStyle with Diagnosticable {
         ifFalse: '$prefix<strut height normal>',
       ),
     );
+    if (height != null) {
+      styles.add(
+        EnumProperty<TextLeadingDistribution>(
+          '${prefix}leadingDistribution',
+          leadingDistribution,
+          defaultValue: null,
+        ),
+      );
+    }
 
     final bool styleSpecified = styles.any(
       (DiagnosticsNode n) => !n.isFiltered(DiagnosticLevel.info),

packages/flutter/test/painting/strut_style_test.dart

@@ -27,5 +27,16 @@ void main() {
 
     const StrutStyle s5 = StrutStyle(forceStrutHeight: true);
     expect(s5.toString(), equals('StrutStyle(<strut height forced>)'));
+
+    const StrutStyle s6 = StrutStyle(height: 14, leadingDistribution: TextLeadingDistribution.even);
+    expect(s6.toString(), equals('StrutStyle(height: 14.0x, leadingDistribution: even)'));
+
+    const StrutStyle s7 = StrutStyle(
+      height: 14,
+      leadingDistribution: TextLeadingDistribution.proportional,
+    );
+    expect(s7.toString(), equals('StrutStyle(height: 14.0x, leadingDistribution: proportional)'));
+
+    expect(s6, isNot(equals(s7)));
   });
 }