fixed charset handing

lib/single-file/single-file-browser.js

@@ -79,11 +79,20 @@ this.SingleFile = this.SingleFile || (() => {
 				resourceContent = options && options.asDataURI ? "data:base64," : "";
 			}
 			let contentType = resourceContent.headers && resourceContent.headers.get("content-type");
+			let charSet;
 			if (contentType) {
-				contentType = contentType.match(/^([^;]*)/)[0].toLowerCase();
+				const matchContentType = contentType.toLowerCase().split(";");
+				contentType = matchContentType[0].trim();
 				if (contentType.indexOf("/") <= 0) {
 					contentType = null;
 				}
+				const charSetValue = matchContentType[1] && matchContentType[1].trim();
+				if (charSetValue) {
+					const matchCharSet = charSetValue.match(/^charset=(.*)/);
+					if (matchCharSet) {
+						charSet = matchCharSet[1];
+					}
+				}
 			}
 			if (options && options.asDataURI) {
 				try {
@@ -101,10 +110,11 @@ this.SingleFile = this.SingleFile || (() => {
 					return "data:base64,";
 				}
 			} else {
-				const matchCharset = contentType && contentType.match(/\s*;\s*charset\s*=\s*"?([^";]*)"?(;|$)/i);
-				let charSet;
-				if (matchCharset && matchCharset[1] || options.charSet) {
-					charSet = (matchCharset && matchCharset[1].toLowerCase()) || options.charSet;
+				if (!charSet) {
+					const matchCharset = contentType && contentType.match(/\s*;\s*charset\s*=\s*"?([^";]*)"?(;|$)/i);
+					if (matchCharset && matchCharset[1] || options.charSet) {
+						charSet = (matchCharset && matchCharset[1].toLowerCase()) || options.charSet;
+					}
 				}
 				if (!charSet) {
 					charSet = "utf-8";