textureData updated to fix flipping property for webgl

Author: MuktiMishra

src/webgl/p5.Texture.js

@@ -126,7 +126,12 @@ p5.Texture = class Texture {
     this.isSrcHTMLElement
     ) {
     // if param is a video HTML element
-      textureData = this.src.elt;
+      // UPDATED:
+      if (this.src._ensureCanvas) {
+        this.src._ensureCanvas()
+      }
+      textureData = this.src.canvas || this.src.elt;
+      // End update
     } else if (this.isImageData) {
       textureData = this.src;
     }