Reverting handling of blob imports

package.json

@@ -1,6 +1,6 @@
 {
 	"name": "upad-parse",
-	"version": "6.2.3",
+	"version": "6.2.4",
 	"description": "This is a parser for the NPX file format that µPad uses",
 	"main": "dist/index.js",
 	"scripts": {

src/Translators.ts

@@ -377,7 +377,23 @@ export namespace Translators {
 		export type MarkdownImport = { title: string, content: string };
 	}
 
+	// Thanks to http://stackoverflow.com/a/12300351/998467
 	async function dataURItoBlob(dataURI: string) {
-		return fetch(dataURI).then(res => res.blob());
+		// convert base64 to raw binary data held in a string
+		// doesn't handle URLEncoded DataURIs - see SO answer #6850276 for code that does this
+		let byteString = atob(dataURI.split(',')[1]);
+
+		// separate out the mime component
+		let mimeString = dataURI.split(',')[0].split(':')[1].split(';')[0];
+
+		// write the bytes of the string to an ArrayBuffer
+		let ab = new ArrayBuffer(byteString.length);
+		let ia = new Uint8Array(ab);
+		for (let i = 0; i < byteString.length; i++) {
+			ia[i] = byteString.charCodeAt(i);
+		}
+
+		// write the ArrayBuffer to a blob, and you're done
+		return new Blob([ia], { type: mimeString });
 	}
 }