get y should return this._y in GradientSlider.js

https://bugs.webkit.org/show_bug.cgi?id=274094

Reviewed by Devin Rousso.

Delete get y() and set (y).
Add this._updateTransform() in _handleMousemove because set y() was removed where it was originally set.

* Source/WebInspectorUI/UserInterface/Views/GradientSlider.js:
(WI.GradientSliderKnob.prototype._handleMousemove):
(WI.GradientSliderKnob.prototype.get y): Deleted.
(WI.GradientSliderKnob.prototype.set y): Deleted.

Canonical link: https://commits.webkit.org/278904@main

Source/WebInspectorUI/UserInterface/Views/GradientSlider.js

@@ -317,16 +317,6 @@ WI.GradientSliderKnob = class GradientSliderKnob extends WI.Object
         this._updateTransform();
     }
 
-    get y()
-    {
-        return this._x;
-    }
-
-    set y(y) {
-        this._y = y;
-        this._updateTransform();
-    }
-
     get wellColor()
     {
         return this._wellColor;
@@ -414,9 +404,10 @@ WI.GradientSliderKnob = class GradientSliderKnob extends WI.Object
             x = Math.min(Math.max(0, x), w);
         this.x = x;
 
-        if (this._detaching)
-            this.y = event.pageY - this._startMouseY;
-        else if (this.delegate && typeof this.delegate.knobXDidChange === "function")
+        if (this._detaching) {
+            this._y = event.pageY - this._startMouseY;
+            this._updateTransform();
+        } else if (this.delegate && typeof this.delegate.knobXDidChange === "function")
             this.delegate.knobXDidChange(this);
     }