static/tinymce/tiny_mce_src.js
function hasRightSideBr() {
				var walker = new TreeWalker(container, parentBlock), node;

				while (node = walker.current()) {
					if (node.nodeName == 'BR') {
						return true;
					}

					node = walker.next();
				}
			}
function hasRightSideBr() {
				var walker = new TreeWalker(container, parentBlock), node;

				while (node = walker.current()) {
					if (node.nodeName == 'BR') {
						return true;
					}

					node = walker.next();
				}
			}
function hasRightSideBr ( ) { var walker = new TreeWalker ( container , parentBlock ) , node ; while ( node = walker . current ( ) ) { if ( node . nodeName == 'BR' ) { return true ; } node = walker . next ( ) ; } }
Walks the parent block to the right and look for BR elements
Walks the parent block to the right and look for BR elements