Fix "everything passes, travis fails"

.travis.yml

@@ -25,8 +25,8 @@ script:
 
   - echo 'makeZipFile' && echo -en 'travis_fold:start:script.makeZipFile\\r'
   - npm run clean
-  - npm run makeZipFile -- --concurrency 2
-  - npm pack
+  - npm run makeZipFile -- --concurrency 1
+  - npm pack &> /dev/null
   - echo -en 'travis_fold:end:script.makeZipFile\\r'
 
   - echo 'buildApps' && echo -en 'travis_fold:start:script.buildApps\\r'

gulpfile.js

@@ -43,20 +43,13 @@ var travisDeployUrl = 'http://cesium-dev.s3-website-us-east-1.amazonaws.com/cesi
 //per-task variables.  We use the command line argument here to detect which task is being run.
 var taskName = process.argv[2];
 var noDevelopmentGallery = taskName === 'release' || taskName === 'makeZipFile';
-var buildingRelease = noDevelopmentGallery;
 var minifyShaders = taskName === 'minify' || taskName === 'minifyRelease' || taskName === 'release' || taskName === 'makeZipFile' || taskName === 'buildApps';
 
 var concurrency = yargs.argv.concurrency;
 if (!concurrency) {
     concurrency = os.cpus().length;
 }
 
-//Since combine and minify run in parallel already, split concurrency in half when building both.
-//This can go away when gulp 4 comes out because it allows for synchronous tasks.
-if (buildingRelease) {
-    concurrency = concurrency / 2;
-}
-
 var sourceFiles = ['Source/**/*.js',
                    '!Source/*.js',
                    '!Source/Workers/**',
@@ -178,14 +171,16 @@ gulp.task('cloc', ['clean'], function() {
     });
 });
 
-gulp.task('combine', ['generateStubs'], function() {
+function combine() {
     var outputDirectory = path.join('Build', 'CesiumUnminified');
     return combineJavaScript({
-        removePragmas : false,
-        optimizer : 'none',
-        outputDirectory : outputDirectory
+        removePragmas: false,
+        optimizer: 'none',
+        outputDirectory: outputDirectory
     });
-});
+}
+
+gulp.task('combine', ['generateStubs'], combine);
 
 gulp.task('combineRelease', ['generateStubs'], function() {
     var outputDirectory = path.join('Build', 'CesiumUnminified');
@@ -197,7 +192,7 @@ gulp.task('combineRelease', ['generateStubs'], function() {
 });
 
 //Builds the documentation
-gulp.task('generateDocumentation', function() {
+function generateDocumentation() {
     var envPathSeperator = os.platform() === 'win32' ? ';' : ':';
 
     return new Promise(function(resolve, reject) {
@@ -216,7 +211,8 @@ gulp.task('generateDocumentation', function() {
             return streamToPromise(stream).then(resolve);
         });
     });
-});
+}
+gulp.task('generateDocumentation', generateDocumentation);
 
 gulp.task('instrumentForCoverage', ['build'], function(done) {
     var jscoveragePath = path.join('Tools', 'jscoverage-0.5.1', 'jscoverage.exe');
@@ -286,13 +282,15 @@ gulp.task('minify', ['generateStubs'], function() {
     });
 });
 
-gulp.task('minifyRelease', ['generateStubs'], function() {
+function minifyRelease() {
     return combineJavaScript({
-        removePragmas : true,
-        optimizer : 'uglify2',
-        outputDirectory : path.join('Build', 'Cesium')
+        removePragmas: true,
+        optimizer: 'uglify2',
+        outputDirectory: path.join('Build', 'Cesium')
     });
-});
+}
+
+gulp.task('minifyRelease', ['generateStubs'], minifyRelease);
 
 function isTravisPullRequest() {
     return process.env.TRAVIS_PULL_REQUEST !== undefined && process.env.TRAVIS_PULL_REQUEST !== 'false';
@@ -592,7 +590,11 @@ function setStatus(state, targetUrl, description, context) {
      });
 }
 
-gulp.task('release', ['combine', 'minifyRelease', 'generateDocumentation']);
+gulp.task('release', ['generateStubs'], function() {
+    return combine()
+        .then(minifyRelease)
+        .then(generateDocumentation);
+});
 
 gulp.task('test', function(done) {
     var argv = yargs.argv;
@@ -1215,7 +1217,7 @@ function buildSandcastle() {
         })
         .pipe(gulp.dest('Build/Apps/Sandcastle'));
 
-    return eventStream.merge(appStream, imageStream);
+    return streamToPromise(eventStream.merge(appStream, imageStream));
 }
 
 function buildCesiumViewer() {