Only ignore build dir under dart dir

Have the shredder ignore `**/dart/build/**`.

Author: chalin

tools/doc-shredder/doc-shredder.js

@@ -138,7 +138,7 @@ function createShredExamplePackage(shredOptions) {
       readFilesProcessor.sourceFiles = [ {
         // Process all candidate files in `src` and its subfolders ...
         include: includeFiles ,
-        exclude: [ '**/node_modules/**', '**/dist/**', '**/typings/**', '**/packages/**', '**/build/**'],
+        exclude: [ '**/node_modules/**', '**/dist/**', '**/typings/**', '**/packages/**', '**/dart/build/**'],
         // When calculating the relative path to these files use this as the base path.
         // So `src/foo/bar.js` will have relative path of `foo/bar.js`
         basePath: options.examplesDir
@@ -190,7 +190,7 @@ function createShredJadePackage(shredOptions) {
       readFilesProcessor.sourceFiles = [ {
         // Process all candidate files in `src` and its subfolders ...
         include: includeFiles ,
-        exclude: [ '**/node_modules/**', '**/typings/**', '**/packages/**', '**/build/**', '**/_code-examples.jade'],
+        exclude: [ '**/node_modules/**', '**/typings/**', '**/packages/**', '**/dart/build/**', '**/_code-examples.jade'],
         // When calculating the relative path to these files use this as the base path.
         // So `src/foo/bar.js` will have relative path of `foo/bar.js`
         basePath: options.jadeDir
@@ -244,7 +244,7 @@ var createShredMapPackage = function(mapOptions) {
       readFilesProcessor.sourceFiles = [ {
         // Process all candidate files in `src` and its subfolders ...
         include: includeFiles,
-        exclude: ['**/node_modules/**', '**/typings/**', '**/packages/**', '**/build/**'],
+        exclude: ['**/node_modules/**', '**/typings/**', '**/packages/**', '**/dart/build/**'],
         // When calculating the relative path to these files use this as the base path.
         // So `src/foo/bar.js` will have relative path of `foo/bar.js`
         basePath: options.jadeDir