Update WebGLTextureUtils.js (#30236) (#30238)

Fixed a typo in a function name.

src/renderers/webgl-fallback/utils/WebGLTextureUtils.js

@@ -731,7 +731,7 @@ class WebGLTextureUtils {
 
 		const requireDrawFrameBuffer = texture.isDepthTexture === true || ( renderContext.renderTarget && renderContext.renderTarget.samples > 0 );
 
-		const srcHeight = renderContext.renderTarget ? renderContext.renderTarget.height : this.backend.gerDrawingBufferSize().y;
+		const srcHeight = renderContext.renderTarget ? renderContext.renderTarget.height : this.backend.getDrawingBufferSize().y;
 
 		if ( requireDrawFrameBuffer ) {