Add common grunt tasks and utils

- readManifest: process recursive build.json's
- grunt task copy-sourcemap: copy the sourcesContent from sourceMapA to sourceMapB

loader/readManifest.js

@@ -0,0 +1,26 @@
+// recursive module loader
+var fs = require('fs');
+var path = require('path');
+
+function readJSON(filename) {
+  var blob = fs.readFileSync(filename, 'utf8');
+  return JSON.parse(blob);
+}
+
+function readManifest(filename, modules) {
+  modules = modules || [];
+  var lines = readJSON(filename);
+  var dir = path.dirname(filename);
+  lines.forEach(function(line) {
+    var fullpath = path.join(dir, line);
+    if (line.slice(-5) == '.json') {
+      // recurse
+      readManifest(fullpath, modules);
+    } else {
+      modules.push(fullpath);
+    }
+  });
+  return modules;
+}
+
+module.exports = readManifest;

tasks/copy-sourcemap.js

@@ -0,0 +1,14 @@
+module.exports = function(grunt) {
+  grunt.registerTask('sourcemap_copy', 'Copy sourcesContent between sourcemaps', function(source, dest) {
+    var sourceMap = grunt.file.readJSON(source);
+    var destMap = grunt.file.readJSON(dest);
+    destMap.sourcesContent = [];
+    var ssources = sourceMap.sources;
+    // uglify may reorder sources, make sure sourcesContent matches new order
+    destMap.sources.forEach(function(source) {
+      var j = ssources.indexOf(source);
+      destMap.sourcesContent.push(sourceMap.sourcesContent[j]);
+    });
+    grunt.file.write(dest, JSON.stringify(destMap));
+  });
+};