Don't increment both start and end points if they are the same object (e.g. no selection)

src/js/simplemde.js

@@ -399,8 +399,10 @@ function _replaceSelection(cm, active, start, end) {
 		cm.replaceSelection(start + text + end);
 
 		startPoint.ch += start.length;
+		if(startPoint !== endPoint) {
 			endPoint.ch += start.length;
 		}
+	}
 	cm.setSelection(startPoint, endPoint);
 	cm.focus();
 }
@@ -552,11 +554,15 @@ function _toggleBlock(editor, type, start_chars, end_chars) {
 
 		if(type == "bold" || type == "strikethrough") {
 			startPoint.ch -= 2;
+			if(startPoint !== endPoint) {
 				endPoint.ch -= 2;
+			}
 		} else if(type == "italic") {
 			startPoint.ch -= 1;
+			if(startPoint !== endPoint) {
 				endPoint.ch -= 1;
 			}
+		}
 	} else {
 		text = cm.getSelection();
 		if(type == "bold") {