remove leading whitespace in paragraphs

Spec:
No leading whitespace within a paragraph

Fix:
I strip leading whitespace on each line while rendering paragraphs

Unanticipated problem:
Causes the (previously failing but hidden) CommonMark 318 to fail.
I added that to the list of expected-to-fail tests.

This commit addresses a failing header test case noted in 943d995
whose root cause was paragraph rendering not up to spec.

lib/marked.js

@@ -534,7 +534,7 @@ if (NEW_TEXT) {
   //       we break the definition of GFM inline.breaks further down (affects the gfm_break test).
   // Furthermore, we still have trouble with the email pattern substituted in: /|[...]+@/, which
   // is vulnerable to REDOS just like /| {2,}\n/ was
-  inline.text = /[\s\S](?:[\\<!\[`*]|\b_|  \n|$)/;
+  inline.text = /[\s\S](?:[\\<!\[`*]|\b_| {2}\n|$)/;
 }
 
 inline._escapes = /\\([!"#$%&'()*+,\-./:;<=>?@\[\]\\^_`{|}~])/g;
@@ -961,7 +961,12 @@ Renderer.prototype.listitem = function(text) {
 };
 
 Renderer.prototype.paragraph = function(text) {
-  return '<p>' + text + '</p>\n';
+  var lines = text.split(/\n/);
+  lines = lines.map(function(l) {
+    return l.replace(/^ +/, '');
+  });
+
+  return '<p>' + lines.join('\n') + '</p>\n';
 };
 
 Renderer.prototype.table = function(header, body) {
@@ -1390,7 +1395,6 @@ function rtrim(str, c, allButC) {
   return str.substr(0, curr);
 }
 
-
 /**
  * Marked
  */

test/specs/commonmark/commonmark-spec.js

@@ -94,8 +94,7 @@ describe('CommonMark 0.28 Precedence', function() {
 describe('CommonMark 0.28 Thematic breaks', function() {
   var section = 'Thematic breaks';
 
-  // var shouldPassButFails = [];
-  var shouldPassButFails = [19];
+  var shouldPassButFails = [];
 
   var willNotBeAttemptedByCoreTeam = [];
 
@@ -109,8 +108,7 @@ describe('CommonMark 0.28 Thematic breaks', function() {
 describe('CommonMark 0.28 ATX headings', function() {
   var section = 'ATX headings';
 
-  // var shouldPassButFails = [];
-  var shouldPassButFails = [40];
+  var shouldPassButFails = [];
 
   var willNotBeAttemptedByCoreTeam = [];
 
@@ -139,8 +137,7 @@ describe('CommonMark 0.28 Setext headings', function() {
 describe('CommonMark 0.28 Indented code blocks', function() {
   var section = 'Indented code blocks';
 
-  // var shouldPassButFails = [];
-  var shouldPassButFails = [82];
+  var shouldPassButFails = [];
 
   var willNotBeAttemptedByCoreTeam = [];
 
@@ -198,8 +195,7 @@ describe('CommonMark 0.28 Link reference definitions', function() {
 describe('CommonMark 0.28 Paragraphs', function() {
   var section = 'Paragraphs';
 
-  // var shouldPassButFails = [];
-  var shouldPassButFails = [185, 186];
+  var shouldPassButFails = [];
 
   var willNotBeAttemptedByCoreTeam = [];
 
@@ -319,7 +315,7 @@ describe('CommonMark 0.28 Code spans', function() {
   var section = 'Code spans';
 
   // var shouldPassButFails = [];
-  var shouldPassButFails = [330, 316, 328, 320, 323, 322];
+  var shouldPassButFails = [330, 316, 318, 328, 320, 323, 322];
 
   var willNotBeAttemptedByCoreTeam = [];
 
@@ -349,7 +345,7 @@ describe('CommonMark 0.28 Links', function() {
   var section = 'Links';
 
   // var shouldPassButFails = [];
-  var shouldPassButFails = [468, 474, 478, 483, 489, 490, 491, 492, 495, 496, 497, 499, 503, 504, 505, 507, 508, 509, 523, 535];
+  var shouldPassButFails = [468, 474, 478, 483, 489, 490, 491, 492, 495, 496, 497, 499, 503, 504, 505, 507, 508, 509, 535];
 
   var willNotBeAttemptedByCoreTeam = [];