internal/graphicsdriver/opengl: remove fnIsContextLost

As restoring from context lost doesn't happen on browsers, isContextLost
doesn't have to be called.

internal/graphicsdriver/graphics.go

@@ -15,8 +15,6 @@
 package graphicsdriver
 
 import (
-	"errors"
-
 	"github.com/hajimehoshi/ebiten/v2/internal/graphics"
 	"github.com/hajimehoshi/ebiten/v2/internal/shaderir"
 )
@@ -60,9 +58,6 @@ type Graphics interface {
 	DrawTriangles(dst ImageID, srcs [graphics.ShaderImageCount]ImageID, shader ShaderID, dstRegions []DstRegion, indexOffset int, blend Blend, uniforms [][]uint32, evenOdd bool) error
 }
 
-// GraphicsNotReady represents that the graphics driver is not ready for recovering from the context lost.
-var GraphicsNotReady = errors.New("graphics not ready")
-
 type Image interface {
 	ID() ImageID
 	Dispose()

internal/graphicsdriver/opengl/context_js.go

@@ -48,8 +48,6 @@ type contextImpl struct {
 	ctx    gl.Context
 	canvas js.Value
 	webGL2 bool
-
-	fnIsContextLost js.Value
 }
 
 func (c *context) reset() error {
@@ -60,9 +58,6 @@ func (c *context) reset() error {
 	c.lastViewportHeight = 0
 	c.lastBlend = graphicsdriver.Blend{}
 
-	if c.fnIsContextLost.Invoke().Bool() {
-		return graphicsdriver.GraphicsNotReady
-	}
 	c.ctx.Enable(gl.BLEND)
 	c.ctx.Enable(gl.SCISSOR_TEST)
 	c.blend(graphicsdriver.BlendSourceOver)

internal/graphicsdriver/opengl/graphics_js.go

@@ -62,7 +62,6 @@ func NewGraphics(canvas js.Value) (graphicsdriver.Graphics, error) {
 	g.context.canvas = canvas
 	g.context.ctx = ctx
 	g.context.webGL2 = webGL2
-	g.context.fnIsContextLost = glContext.Get("isContextLost").Call("bind", glContext)
 
 	if !webGL2 {
 		glContext.Call("getExtension", "OES_standard_derivatives")

internal/restorable/images.go

@@ -109,11 +109,7 @@ func RestoreIfNeeded(graphicsDriver graphicsdriver.Graphics) error {
 		}
 	}
 
-	err := graphicscommand.ResetGraphicsDriverState(graphicsDriver)
-	if err == graphicsdriver.GraphicsNotReady {
-		return nil
-	}
-	if err != nil {
+	if err := graphicscommand.ResetGraphicsDriverState(graphicsDriver); err != nil {
 		return err
 	}
 	return theImages.restore(graphicsDriver)