internal/graphicsdriver/opengl: Give up restorign on browsers

Using restorable images is expensive as this sometimes requires to
load pixels from GPU. On browsers, just reloading the application
should be fine when the context lost happens.

Closes #1603

internal/graphicsdriver/opengl/context_js.go

@@ -23,7 +23,6 @@ import (
 	"github.com/hajimehoshi/ebiten/v2/internal/graphicsdriver/opengl/gles"
 	"github.com/hajimehoshi/ebiten/v2/internal/jsutil"
 	"github.com/hajimehoshi/ebiten/v2/internal/shaderir"
-	"github.com/hajimehoshi/ebiten/v2/internal/web"
 )
 
 type (
@@ -85,7 +84,6 @@ const (
 
 var (
 	isWebGL2Available = !forceWebGL1 && (js.Global().Get("WebGL2RenderingContext").Truthy() || js.Global().Get("go2cpp").Truthy())
-	needsRestoring    = !web.IsMobileBrowser() && !js.Global().Get("go2cpp").Truthy()
 )
 
 type contextImpl struct {
@@ -526,7 +524,8 @@ func (c *context) flush() {
 }
 
 func (c *context) needsRestoring() bool {
-	return needsRestoring
+	// Though it is possible to have a logic to restore the graphics data for GPU, do not use it for performance (#1603).
+	return false
 }
 
 func (c *context) canUsePBO() bool {