fixed srcdoc formatting

lib/single-file/single-file-core.js

@@ -460,7 +460,7 @@ this.SingleFileCore = (() => {
 			await Promise.all(frameElements.map(async (frameElement, frameIndex) => {
 				const frameWindowId = (this.options.windowId || "0") + "." + frameIndex;
 				const frameData = this.options.framesData.find(frame => frame.windowId == frameWindowId);
-				const setFrameEmptySrc = frameElement => frameElement.setAttribute(frameElement.tagName == "OBJECT" ? "data" : "src", EMPTY_DATA_URI);
+				const setFrameEmptySrc = frameElement => frameElement.setAttribute(frameElement.tagName == "OBJECT" ? "data" : "srcdoc", (frameElement.tagName == "OBJECT" ? "data:text/html," : ""));
 				if (frameData) {
 					if (initialization) {
 						const options = Object.create(this.options);
@@ -479,7 +479,7 @@ this.SingleFileCore = (() => {
 						setFrameEmptySrc(frameElement);
 						if (frameData.processor) {
 							const pageData = await frameData.processor.getPageData();
-							frameElement.setAttribute(frameElement.tagName == "OBJECT" ? "data" : "srcdoc", (frameElement.tagName != "OBJECT" ? "data:text/html," : "") + pageData.content);
+							frameElement.setAttribute(frameElement.tagName == "OBJECT" ? "data" : "srcdoc", (frameElement.tagName == "OBJECT" ? "data:text/html," : "") + pageData.content);
 							frameElement.sandbox = true;
 						}
 					}