Merge pull request #15981 from mrdoob/revert-15062-dev-line_clone_copy

Revert "Line: fix copy and clone methods"

src/objects/Line.js

@@ -244,20 +244,9 @@ Line.prototype = Object.assign( Object.create( Object3D.prototype ), {
 
 	}() ),
 
-	copy: function ( source ) {
-
-		Object3D.prototype.copy.call( this, source );
-
-		this.geometry.copy( source.geometry );
-		this.material.copy( source.material );
-
-		return this;
-
-	},
-
 	clone: function () {
 
-		return new this.constructor().copy( this );
+		return new this.constructor( this.geometry, this.material ).copy( this );
 
 	}