Merge branch 'master' into a11y-tab

Author: tinayuangao

.github/CODEOWNERS

@@ -49,7 +49,8 @@ src/lib/core/datetime/**           @mmalerba
 # CDK
 src/cdk/coercion/**                @jelbourn
 src/cdk/rxjs/**                    @jelbourn
-src/cdk/observers/**               @crisbeto @jelbourn
+src/cdk/observers/**               @jelbourn @crisbeto
+src/cdk/collections/**             @jelbourn @crisbeto @andrewseguin
 src/cdk/a11y/**                    @jelbourn @devversion
 src/cdk/platform/**                @jelbourn @devversion
 src/cdk/bidi/**                    @jelbourn

.travis.yml

@@ -3,7 +3,7 @@ sudo: false
 dist: trusty
 
 node_js:
-  - '--lts'
+  - '8'
 
 addons:
   jwt:
@@ -43,7 +43,6 @@ env:
 
 before_install:
   - source ./scripts/ci/travis-env.sh
-  - npm i -g npm@^5.3.0
 
 install:
   - npm install
@@ -56,4 +55,4 @@ script:
 
 cache:
   directories:
-    - $HOME/.npm
+    - ./node_modules/