Bug 270955

Created attachment 470359 [details] Sample App where this issue can be replicated. I am encountering an issue with canvas rendering in Safari, where my drawing application, functioning smoothly on Chrome, exhibits delayed rendering behavior in Safari. Specifically, when clicking a button to draw a triangle on the canvas, it often requires multiple clicks (sometimes 3-4) to render the triangle as expected. Observations: Adding glFinish() after glDrawArrays resolves the issue, while glFlush() does not. Confirmed that the main thread is not blocked during the rendering process through logging. Attempted to call emscripten_webgl_commit_frame() after glDrawArrays at regular intervals, but the issue persists. The function consistently returns EMSCRIPTEN_RESULT_SUCCESS. Steps to Reproduce: Open the drawing application in Safari. Click the button to draw a triangle on the canvas. Observe that the triangle does not render on the first click and may require multiple clicks for rendering.