Clarify --add-prefetch build flag (#510)

* rename confusing --insert-dependency-links flag to --prefetch-dependencies

* rename prefetchDepedencies to addPrefetchLinks

* rename to insert-prefetch-links

src/build/build.ts

@@ -34,7 +34,7 @@ const buildDirectory = 'build/';
 
 export interface BuildOptions {
   swPrecacheConfig?: string;
-  insertDependencyLinks?: boolean;
+  insertPrefetchLinks?: boolean;
   bundle?: boolean;
   // TODO(fks) 07-21-2016: Fully complete these with available options
   html?: {collapseWhitespace?: boolean; removeComments?: boolean};
@@ -56,11 +56,6 @@ export async function build(
     js: Object.assign({minify: true}, options.js),
   };
 
-  if (options.insertDependencyLinks) {
-    logger.debug(
-        `Additional dependency links will be inserted into application`);
-  }
-
   logger.info(`Deleting build/ directory...`);
   await del([buildDirectory]);
 
@@ -96,10 +91,10 @@ export async function build(
 
   if (options.bundle) {
     buildStream = buildStream.pipe(polymerProject.bundler);
-  } else {
-    buildStream = buildStream.pipe(gulpif(
-        options.insertDependencyLinks || false,
-        new PrefetchTransform(polymerProject)));
+  }
+
+  if (options.insertPrefetchLinks) {
+    buildStream = buildStream.pipe(new PrefetchTransform(polymerProject));
   }
 
   buildStream = buildStream

src/commands/build.ts

@@ -45,11 +45,12 @@ export class BuildCommand implements Command {
           'used for service worker generation.'
     },
     {
-      name: 'insert-dependency-links',
+      name: 'insert-prefetch-links',
       type: Boolean,
-      description: 'Flatten dependency tree downloads by inserting ' +
-          'additional `<link rel="prefetch">` tags into ' +
-          'entrypoint and `<link rel="import">` tags into fragments and shell.'
+      description: 'Add dependency prefetching by inserting ' +
+          '`<link rel="prefetch">` tags into entrypoint and ' +
+          '`<link rel="import">` tags into fragments and shell for all ' +
+          'dependencies.'
     },
     {
       name: 'html.collapseWhitespace',
@@ -64,7 +65,7 @@ export class BuildCommand implements Command {
 
     let buildOptions: BuildOptions = {
       swPrecacheConfig: options['sw-precache-config'],
-      insertDependencyLinks: options['insert-dependency-links'],
+      insertPrefetchLinks: options['insert-prefetch-links'],
       bundle: options['bundle'],
       html: {},
       css: {},