fix(brocolli): escape special regexp characters when building regexps

Special regexp tokens were allowed unchanged previously, which incorrectly broke
the include/exclude behaviour. Now, they're escaped first.

Closes angular#1721
Closes angular#1752

Author: caitp

tools/broccoli/tree-differ.spec.ts

@@ -151,6 +151,7 @@ describe('TreeDiffer', () => {
         'dir1': {
           'file-1.ts': mockfs.file({content: 'file-1.ts content', mtime: new Date(1000)}),
           'file-1.cs': mockfs.file({content: 'file-1.cs content', mtime: new Date(1000)}),
+          'file-1d.cs': mockfs.file({content: 'file-1d.cs content', mtime: new Date(1000)}),
           'file-1.d.cs': mockfs.file({content: 'file-1.d.cs content', mtime: new Date(1000)}),
           'file-2.md': mockfs.file({content: 'file-2.md content', mtime: new Date(1000)}),
           'file-3.ts': mockfs.file({content: 'file-3.ts content', mtime: new Date(1000)}),
@@ -166,7 +167,8 @@ describe('TreeDiffer', () => {
 
       let diffResult = differ.diffTree();
 
-      expect(diffResult.changedPaths).toEqual(['file-1.cs', 'file-1.ts', 'file-3.ts']);
+      expect(diffResult.changedPaths)
+          .toEqual(['file-1.cs', 'file-1.ts', 'file-1d.cs', 'file-3.ts']);
 
       // change two files
       testDir['dir1']['file-1.ts'] = mockfs.file({content: 'new content', mtime: new Date(1000)});

tools/broccoli/tree-differ.ts

@@ -22,7 +22,8 @@ export class TreeDiffer {
 
     function combine(prev, curr) {
       if (curr.charAt(0) !== ".") throw new TypeError("Extension must begin with '.'");
-      curr = '(' + curr + ')';
+      let kSpecialRegexpChars = /[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g;
+      curr = '(' + curr.replace(kSpecialRegexpChars, '\\$&') + ')';
       return prev ? (prev + '|' + curr) : curr;
     }
   }