WebGLMultipleRenderTargets: Copy viewport/scissor from source.

[querielo]

The PR fixes a misprint.

It looks like we have to copy source.viewport/source.scissor instead of cleaning this.viewport/this.scissor:

		this.viewport.set( 0, 0, this.width, this.height );
		this.scissor.set( 0, 0, this.width, this.height );

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

Filesize	Gzipped	Diff from dev
633.5 kB	157 kB	-31 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

Filesize	Gzipped	Diff from dev
424.8 kB	103 kB	+0 B