Strip generated <p> tags in dataToDom

domToData wraps bare content in paragraph elements, which were then
converted to <p> tags by domToData. With this fix, HTML with "missing"
<p> tags actually round-trips through the editor correctly now, rather
than having <p> tags added wherever VE believes they should exist.

* Mark generated paragraph elements with .internal.generated = 'wrapper'
** This signifies the wrapper was generated but its contents were not,
   so the right thing to do when converting back to HTML is to remove
   the wrapper and keep the contents. We might want to use other values
   of generated in the future.
* Unwrap nodes with generated=wrapper when converting to HTML

Tests:
* Add 'generated': 'wrapper' as appropriate. Only affects 1 test
* Remove 'normalizedHtml' for this test because it is no longer needed
** Need to keep 'normalizedHtml' for now because we normalize hrefs
* Eventually the main example should test bare content, but that
  requires touching a lot of stuff. The main example could use some
  beefing up anyway.

Change-Id: I277ad5fe3f64e07c1bbf49007d6bbaecc90b7466

modules/ve/dm/ve.dm.Converter.js

@@ -275,7 +275,12 @@ ve.dm.Converter.prototype.getDataFromDom = function ( domElement, annotations, d
 				if ( annotation ) {
 					// Start auto-wrapping of bare content
 					if ( !wrapping && !alreadyWrapped && !branchIsContent ) {
-						data.push( { 'type': 'paragraph' } );
+						// Mark this paragraph as having been generated by
+						// us, so we can strip it on the way out
+						data.push( {
+							'type': 'paragraph',
+							'internal': { 'generated': 'wrapper' }
+						} );
 						wrapping = true;
 					}
 					// Append child element data
@@ -328,7 +333,12 @@ ve.dm.Converter.prototype.getDataFromDom = function ( domElement, annotations, d
 
 				// Start auto-wrapping of bare content
 				if ( !wrapping && !alreadyWrapped && !branchIsContent ) {
-					paragraph = { 'type': 'paragraph' };
+					// Mark this paragraph as having been generated by
+					// us, so we can strip it on the way out
+					paragraph = {
+						'type': 'paragraph',
+						'internal': { 'generated': 'wrapper' }
+					};
 					data.push( paragraph );
 					wrapping = true;
 					wrapperElement = paragraph;
@@ -400,7 +410,7 @@ ve.dm.Converter.prototype.getDataFromDom = function ( domElement, annotations, d
 		!ve.dm.nodeFactory.isNodeContent( branchType ) &&
 		( childTypes === null || ve.indexOf( 'paragraph', childTypes ) !== -1 )
 	) {
-		data.push( { 'type': 'paragraph' } );
+		data.push( { 'type': 'paragraph', 'internal': { 'generated': 'wrapper' } } );
 		data.push( { 'type': '/paragraph' } );
 	}
 
@@ -410,7 +420,10 @@ ve.dm.Converter.prototype.getDataFromDom = function ( domElement, annotations, d
 	}
 	// Don't return an empty document
 	if ( branchType === 'document' && data.length === 0 ) {
-		return [{ 'type': 'paragraph' }, { 'type': '/paragraph' }];
+		return [
+			{ 'type': 'paragraph', 'internal': { 'generated': 'wrapper' } },
+			{ 'type': '/paragraph' }
+		];
 	}
 	return data;
 };
@@ -423,8 +436,8 @@ ve.dm.Converter.prototype.getDataFromDom = function ( domElement, annotations, d
  * @returns {HTMLElement} Wrapper div containing the resulting HTML
  */
 ve.dm.Converter.prototype.getDomFromData = function ( data ) {
-	var text, i, annotations,  hash, annotationElement, done, dataElement, wrapper,
-		childDomElement, pre, post,
+	var text, i, j, annotations, hash, annotationElement, done, dataElement, wrapper,
+		childDomElement, pre, post, parentDomElement,
 		container = document.createElement( 'div' ),
 		domElement = container,
 		annotationStack = {}; // { hash: DOMnode }
@@ -572,13 +585,30 @@ ve.dm.Converter.prototype.getDomFromData = function ( data ) {
 						}
 					}
 				}
+
+				// If closing a generated wrapper node, unwrap it
+				// It would be nicer if we could avoid generating in the first
+				// place, but then remembering where we have to skip ascending
+				// to the parent would be tricky.
+				parentDomElement = domElement.parentNode;
+				if ( domElement.veInternal && domElement.veInternal.generated === 'wrapper' ) {
+					for ( j = 0; j < domElement.childNodes.length; j++ ) {
+						parentDomElement.insertBefore(
+							domElement.childNodes[j],
+							domElement
+						);
+					}
+					parentDomElement.removeChild( domElement );
+				}
+
+				// Clean up the internal data
 				delete domElement.veInternal;
 				// Ascend to parent node
-				domElement = domElement.parentNode;
+				domElement = parentDomElement;
 			} else {
 				// Create node from data
 				childDomElement = this.getDomElementFromDataElement( dataElement );
-				// Add reference to internal data to propagate whitespace info
+				// Add reference to internal data
 				if ( dataElement.internal ) {
 					childDomElement.veInternal = dataElement.internal;
 				}

modules/ve/test/dm/ve.dm.example.js

@@ -13,6 +13,7 @@ ve.dm.example = {};
  * Serialized HTML.
  *
  * This is what the parser will emit.
+ * TODO remove some of the <p>s here to test automatic wrapping
  */
 ve.dm.example.html =
 	'<h1>a<b>b</b><i>c</i></h1>' +
@@ -677,26 +678,25 @@ ve.dm.example.domToDataCases = {
 		]
 	},
 	'whitespace preservation in list items': {
-		'normalizedHtml': '<ul><li><p>Foo</p></li><li><p> Bar</p></li><li><p>Baz </p></li><li><p>  Quux   </p></li></ul>',
 		'html': '<ul><li>Foo</li><li> Bar</li><li>Baz </li><li>  Quux   </li></ul>',
 		'data': [
 			{ 'type': 'list', 'attributes': { 'style': 'bullet' } },
 			{ 'type': 'listItem' },
-			{ 'type': 'paragraph' },
+			{ 'type': 'paragraph', 'internal': { 'generated': 'wrapper' } },
 			'F',
 			'o',
 			'o',
 			{ 'type': '/paragraph' },
 			{ 'type': '/listItem' },
 			{ 'type': 'listItem' },
-			{ 'type': 'paragraph', 'internal': { 'whitespace': [ undefined, ' ' ] } },
+			{ 'type': 'paragraph', 'internal': { 'whitespace': [ undefined, ' ' ], 'generated': 'wrapper' } },
 			'B',
 			'a',
 			'r',
 			{ 'type': '/paragraph' },
 			{ 'type': '/listItem' },
 			{ 'type': 'listItem' },
-			{ 'type': 'paragraph', 'internal': { 'whitespace': [ undefined, undefined, ' ' ] } },
+			{ 'type': 'paragraph', 'internal': { 'whitespace': [ undefined, undefined, ' ' ], 'generated': 'wrapper' } },
 			'B',
 			'a',
 			'z',
@@ -705,7 +705,7 @@ ve.dm.example.domToDataCases = {
 			{ 'type': 'listItem' },
 			{
 				'type': 'paragraph',
-				'internal': { 'whitespace': [ undefined, '  ', '   ' ] }
+				'internal': { 'whitespace': [ undefined, '  ', '   ' ], 'generated': 'wrapper' }
 			},
 			'Q',
 			'u',