moved matrix3.flattenToArrayOffset to legacy

src/Three.Legacy.js

@@ -258,6 +258,10 @@ Object.assign( _Math, {
 } );
 
 Object.assign( Matrix3.prototype, {
+	flattenToArrayOffset: function ( array, offset ) {
+		console.warn( "THREE.Matrix3: .flattenToArrayOffset() has been deprecated. Use .toArray() instead." );
+		return this.toArray( array, offset );
+	},
 	multiplyVector3: function ( vector ) {
 		console.warn( 'THREE.Matrix3: .multiplyVector3() has been removed. Use vector.applyMatrix3( matrix ) instead.' );
 		return vector.applyMatrix3( this );

src/math/Matrix3.js

@@ -239,15 +239,6 @@ Matrix3.prototype = {
 
 	},
 
-	flattenToArrayOffset: function ( array, offset ) {
-
-		console.warn( "THREE.Matrix3: .flattenToArrayOffset is deprecated " +
-				"- just use .toArray instead." );
-
-		return this.toArray( array, offset );
-
-	},
-
 	getNormalMatrix: function ( matrix4 ) {
 
 		return this.setFromMatrix4( matrix4 ).getInverse( this ).transpose();