Fix distanceSquaredTo (#3365)

Fix regression and add tests

flixel/math/FlxPoint.hx

@@ -752,7 +752,7 @@ import openfl.geom.Point;
 	 */
 	public overload inline extern function distanceSquaredTo(x:Float, y:Float):Float
 	{
-		return (this.x - x) * (this.x - x) + (this.y - y) + (this.y - y);
+		return (this.x - x) * (this.x - x) + (this.y - y) * (this.y - y);
 	}
 
 	/**

tests/unit/src/flixel/math/FlxPointTest.hx

@@ -44,6 +44,45 @@ class FlxPointTest extends FlxTest
 		Assert.isTrue(yIsInRange);
 	}
 
+	@Test
+	function testDistanceTo():Void
+	{
+		assertDistanceTo(0, 0, 0, 0, 0);
+		assertDistanceTo(0, 0, 1, 0, 1);
+		assertDistanceTo(0, 0, 0, 1, 1);
+		assertDistanceTo(0, 0, -1, 0, 1);
+		assertDistanceTo(0, 0, 0, -1, 1);
+
+		assertDistanceTo(0, 0, 1, 1, Math.sqrt(2));
+		assertDistanceTo(0, 0, -1, 1, Math.sqrt(2));
+		assertDistanceTo(0, 0, 1, -1, Math.sqrt(2));
+		assertDistanceTo(0, 0, -1, -1, Math.sqrt(2));
+
+		assertDistanceTo(3, 4, 0, 0, 5);
+		assertDistanceTo(-3, -4, 0, 0, 5);
+		assertDistanceTo(3, 4, -3, -4, 10);
+
+		assertDistanceTo(5, 5, 10, 10, Math.sqrt(50));
+		assertDistanceTo(-5, -5, -10, -10, Math.sqrt(50));
+
+		assertDistanceTo(7, -3, -2, 6, Math.sqrt(162));
+		assertDistanceTo(-7, 3, 2, -6, Math.sqrt(162));
+	}
+
+	function assertDistanceTo(x0, y0, x1, y1, expected:Float):Void
+	{
+		point1.set(x0, y0);
+		point2.set(x1, y1);
+		FlxAssert.areNear(point1.distanceTo(point2), expected);
+		FlxAssert.areNear(point2.distanceTo(point1), expected);
+		FlxAssert.areNear(point1.dist(point2), expected);
+		FlxAssert.areNear(point2.dist(point1), expected);
+		FlxAssert.areNear(point1.distanceSquaredTo(point2), expected * expected);
+		FlxAssert.areNear(point2.distanceSquaredTo(point1), expected * expected);
+		FlxAssert.areNear(point1.distSquared(point2), expected * expected);
+		FlxAssert.areNear(point2.distSquared(point1), expected * expected);
+	}
+
 	@Test
 	function testDegreesBetween():Void
 	{