Use Uint8ClampedArray for the image data returned by JpegDecode, in src/display/api.js

Since all the built-in PDF.js image decoders now return their data as `Uint8ClampedArray`, for consistency `JpegDecode` on the main-thread should be doing the same thing; follow-up to PR 8778.

src/display/api.js

@@ -2028,7 +2028,7 @@ var WorkerTransport = (function WorkerTransportClosure() {
             var height = img.height;
             var size = width * height;
             var rgbaLength = size * 4;
-            var buf = new Uint8Array(size * components);
+            var buf = new Uint8ClampedArray(size * components);
             var tmpCanvas = document.createElement('canvas');
             tmpCanvas.width = width;
             tmpCanvas.height = height;