chore(doc-gen): render optional members correctly

Partially Closes #2849

docs/angular.io-package/templates/class.template.html

@@ -31,7 +31,7 @@ p.location-badge.
 
 {%- for member in doc.members %}{% if not member.private %}
   .l-sub-section
-    h3 {$ member.name $}
+    h3 {$ member.name $}{% if member.optional %}?{% endif %}
 
     {% if member.parameters %}
     pre.prettyprint

docs/dgeni-package/mocks/readTypeScriptModules/interfaces.ts

@@ -0,0 +1,4 @@
+export interface MyInterface {
+  optionalProperty? : string,
+  (param: string) : string
+}

docs/dgeni-package/processors/readTypeScriptModules.js

@@ -212,6 +212,10 @@ module.exports = function readTypeScriptModules(tsParser, readFilesProcessor, mo
       memberDoc.returnType = getReturnType(typeChecker, memberSymbol);
     }
 
+    if(memberSymbol.flags & ts.SymbolFlags.Optional) {
+      memberDoc.optional = true;
+    }
+
     return memberDoc;
   }
 

docs/dgeni-package/processors/readTypeScriptModules.spec.js

@@ -45,6 +45,22 @@ describe('readTypeScriptModules', function() {
   });
 
 
+  describe('interfaces', function() {
+
+    it('should mark optional properties', function() {
+      processor.sourceFiles = [ 'interfaces.ts'];
+      var docs = [];
+      processor.$process(docs);
+
+      var moduleDoc = docs[0];
+      var exportedInterface = moduleDoc.exports[0];
+      var member = exportedInterface.members[0];
+      expect(member.name).toEqual('optionalProperty');
+      expect(member.optional).toEqual(true);
+    });
+  });
+
+
   describe('ordering of members', function() {
     it('should order class members in order of appearance (by default)', function() {
       processor.sourceFiles = ['orderingOfMembers.ts'];

docs/dgeni-package/templates/class.template.html

@@ -23,7 +23,9 @@ defined in {$ githubViewLink(doc) $}
 
 {%- for member in doc.members %}{% if not member.private %}
   <section class="member">
-    <h1 id="{$ member.name $}" class="name">{$ member.name $}{$ paramList(member.params) $}</h1>
+    <h1 id="{$ member.name $}" class="name">
+      {$ member.name $}{% if member.optional %}?{% endif %}{$ paramList(member.params) $}
+    </h1>
     {% marked %}
       {$ member.description $}
     {% endmarked %}

docs/dgeni-package/templates/type-definition.template.html

@@ -29,6 +29,7 @@ declare module "{$ module.id $}" {
   {%- for member in export.members -%}
     {$ commentBlock(member, 5) $}
     {$ member.name $}
+    {%- if member.optional %}?{% endif -%}
     {%- if member.parameters %}({% for param in member.parameters %}{$ param $}{% if not loop.last %}, {% endif %}{% endfor %}){%- endif %}
     {%- if member.returnType %}: {$ member.returnType $}{%- else -%}: any{% endif -%}
     ;