Use homebrew addon instead of manually executing

.travis.yml

@@ -33,6 +33,23 @@ addons:
     - libgtest-dev
     - gcc-9
     - g++-9
+  homebrew:
+    packages:
+    - autoconf
+    - boost
+    - ffmpeg
+    - ffms2
+    - fftw
+    - freetype
+    - fribidi
+    - gettext
+    - icu4c
+    - libass
+    - lua
+    - luarocks
+    - m4
+    - wxmac
+    update: true
 
 env:
 - ''

.travis/install.sh

@@ -2,12 +2,10 @@
 
 set -e
 
-if [ $TRAVIS_OS_NAME = 'osx' ]; then
-  brew install autoconf ffmpeg freetype gettext ffms2 fftw fribidi libass m4 icu4c boost wxmac lua luarocks
-else
+if [ "$TRAVIS_OS_NAME" = 'linux' ]; then
   # Remove the CMake provided by travis
   sudo rm -rf /usr/local/cmake*
-  if [ "$BUILD_SUIT" = "autotools" ]; then
+  if [ "$BUILD_SUIT" = 'autotools' ]; then
     sudo pip install -U cpp-coveralls;
     git submodule --quiet init;
     git submodule --quiet update vendor/googletest;

README.md

@@ -36,8 +36,8 @@ and optional dependencies:
 You can use the package manager provided by your distro to install these dependencies. Package name varies by distro. Some useful references are:
 
 * For ArchLinux, refer to [AUR](https://aur.archlinux.org/cgit/aur.git/tree/PKGBUILD?h=aegisub-git).
-* For Ubuntu, refer to [Travis](https://github.com/wangqr/Aegisub/blob/dev/.travis.yml#L14-L35).
-* For macOS, refer to [Travis](https://github.com/wangqr/Aegisub/blob/dev/.travis/install.sh#L6). In addition to the packages listed in the `brew install` line, you also need `automake` and `pkg-config`. They are not listed there because Travis preinstalled them. For some packages, you need to either [set environment variables during build](https://github.com/wangqr/Aegisub/blob/dev/.travis.yml#L54-L58) or [force link them](https://github.com/Aegisub/Aegisub/#os-x).
+* For Ubuntu, refer to [Travis](.travis.yml#L14-L35).
+* For macOS, refer to [Travis](.travis.yml#L38-L51). In addition to the packages listed in the `brew install` line, you also need `automake` and `pkg-config`. They are not listed there because Travis preinstalled them. For some packages, you need to either [set environment variables during build](.travis.yml#L71-L75) or [force link them](https://github.com/Aegisub/Aegisub/#os-x).
 
 After installing the dependencies, you can clone and build Aegisub with:
 ```sh