Reverting ArrayCamera WebGLRenderer changes. Viewport gets squashed after entering/leaving VR.

src/renderers/WebGLRenderer.js

@@ -1233,6 +1233,12 @@ function WebGLRenderer( parameters ) {
 		state.buffers.depth.setMask( true );
 		state.buffers.color.setMask( true );
 
+		if ( camera.isArrayCamera && camera.enabled ) {
+
+			_this.setScissorTest( false );
+
+		}
+
 		camera.onAfterRender( _this );
 
 		// _gl.finish();
@@ -1410,19 +1416,15 @@ function WebGLRenderer( parameters ) {
 					var camera2 = cameras[ j ];
 					var bounds = camera2.bounds;
 
-					_currentViewport.set(
-						bounds.x * _width, bounds.y * _height,
-						bounds.z * _width, bounds.w * _height
-					).multiplyScalar( _pixelRatio );
-
-					_currentScissor.set(
-						bounds.x * _width, bounds.y * _height,
-						bounds.z * _width, bounds.w * _height
-					).multiplyScalar( _pixelRatio );
-
-					state.viewport( _currentViewport );
-					state.scissor( _currentScissor );
-					state.setScissorTest( true );
+					_this.setViewport(
+						bounds.x * _width * _pixelRatio, bounds.y * _height * _pixelRatio,
+						bounds.z * _width * _pixelRatio, bounds.w * _height * _pixelRatio
+					);
+					_this.setScissor(
+						bounds.x * _width * _pixelRatio, bounds.y * _height * _pixelRatio,
+						bounds.z * _width * _pixelRatio, bounds.w * _height * _pixelRatio
+					);
+					_this.setScissorTest( true );
 
 					renderObject( object, scene, camera2, geometry, material, group );