CB-9782 Implements PlatformApi contract for Android platform.

This closes #226

node_modules/elementtree/lib/treebuilder.js

@@ -0,0 +1,60 @@
+function TreeBuilder(element_factory) {
+  this._data = [];
+  this._elem = [];
+  this._last = null;
+  this._tail = null;
+  if (!element_factory) {
+    /* evil circular dep */
+    element_factory = require('./elementtree').Element;
+  }
+  this._factory = element_factory;
+}
+
+TreeBuilder.prototype.close = function() {
+  return this._last;
+};
+
+TreeBuilder.prototype._flush = function() {
+  if (this._data) {
+    if (this._last !== null) {
+      var text = this._data.join("");
+      if (this._tail) {
+        this._last.tail = text;
+      }
+      else {
+        this._last.text = text;
+      }
+    }
+    this._data = [];
+  }
+};
+
+TreeBuilder.prototype.data = function(data) {
+  this._data.push(data);
+};
+
+TreeBuilder.prototype.start = function(tag, attrs) {
+  this._flush();
+  var elem = this._factory(tag, attrs);
+  this._last = elem;
+
+  if (this._elem.length) {
+    this._elem[this._elem.length - 1].append(elem);
+  }
+
+  this._elem.push(elem);
+
+  this._tail = null;
+};
+
+TreeBuilder.prototype.end = function(tag) {
+  this._flush();
+  this._last = this._elem.pop();
+  if (this._last.tag !== tag) {
+    throw new Error("end tag mismatch");
+  }
+  this._tail = 1;
+  return this._last;
+};
+
+exports.TreeBuilder = TreeBuilder;