Embed the template AST into the layer file rather than the fully

compiled template.

Template creates dummy elements (ex: <d-button>) for introspection, to
find out when to call element.foo = 123 rather than element.setAttribute("foo", 123).
That of course first requires running the code to define the custom elements.
That wasn't working right during builds, because the javascript files were
referencing symbols that don't exist in Node, such as HTMLElement.

Partial rollback of 2c0633f

Fixes #438, refs #432.

handlebars.js

@@ -90,6 +90,7 @@ define([
 		 * @private
 		 */
 		parse: function (templateNode, xmlns) {
+			/* jshint maxcomplexity:15 */
 			// Get tag name, reversing the tag renaming done in toDom()
 			var tag = templateNode.hasAttribute("is") ? templateNode.getAttribute("is") :
 					templateNode.tagName.replace(/^template-/i, "").toLowerCase(),
@@ -123,14 +124,24 @@ define([
 				}
 			}
 
-			return {
-				tag: tag,
-				xmlns: xmlns,
-				attributes: attributes,
-				connects: connects,
-				children: handlebars.parseChildren(templateNode, xmlns),
-				attachPoints: attachPoints
-			};
+			// Process children.
+			var children = handlebars.parseChildren(templateNode, xmlns);
+
+			// Return AST structure pruning empty arrays etc.  Minimizes size of serialized object.
+			function hasMembers(obj) {
+				/* jshint unused: false */
+				for (var key in obj) {
+					return true;
+				}
+				return false;
+			}
+			var ret = { tag: tag };
+			if (xmlns) { ret.xmlns = xmlns; }
+			if (hasMembers(attributes)) { ret.attributes = attributes; }
+			if (hasMembers(connects)) { ret.connects = connects; }
+			if (children.length) { ret.children = children; }
+			if (hasMembers(attachPoints)) { ret.attachPoints = attachPoints; }
+			return ret;
 		},
 
 		/**
@@ -336,29 +347,26 @@ define([
 			onload();
 		};
 
-		// Inline the template function and list of dependencies into the layer file.
+		// Inline the template AST and list of dependencies into the layer file.
 		handlebars.write = function (pluginName, moduleName, write) {
 			var dom = jsdom(handlebars.neutralizeTags(templateText)),
 				template = dom.querySelector("template-template"),
 				requiresAttr = template.getAttribute("requires") || template.getAttribute("data-requires");
-			templateRequires = requiresAttr && requiresAttr.split(/,\s*/);
+			templateRequires = requiresAttr ? requiresAttr.split(/,\s*/) : [];
 			template.removeAttribute("requires");
 			template.removeAttribute("data-requires");
 
+			var moduleRequires = ["delite/Template"].concat(templateRequires);
 			var tree = handlebars.parse(template);
-			var funcText = (new Template(tree)).func.toString();
-			var moduleText = "define(" + (templateRequires ? JSON.stringify(templateRequires) + ", " : "") +
-				"function(){\n" +
-				"\treturn " + funcText + ";" +
+			var moduleText = "define(" + JSON.stringify(moduleRequires) + ", function(Template){\n" +
+				"\treturn (new Template(" + JSON.stringify(tree) + ")).func;\n" +
 				"});";
 			write.asModule(pluginName + "!" + moduleName, moduleText);
 		};
 
 		// Notify builder to take dependencies specified in requires="..." attribute, and inline them into the layer.
 		handlebars.addModules = function (pluginName, resource, addModules) {
-			if (templateRequires) {
-				addModules(templateRequires);
-			}
+			addModules(templateRequires);
 		};
 	}