Use precompiled cargo-web on Travis

Author: koute

.travis.yml

@@ -130,10 +130,7 @@ matrix:
         - rustup target add wasm32-unknown-unknown
         - rustup target add wasm32-unknown-emscripten
         - nvm install 9
-        # cargo-web takes ±10 min. to install, and cargo and cargo-update offer
-        # no reliable update-or-install command. We ignore updating for now
-        # (just drop the Travis' caches when necessary)
-        - cargo --list | egrep "^\s*web$" -q || cargo install cargo-web
+        - ./utils/ci/install_cargo_web.sh
         - cargo web -V
       addons:
         chrome: stable

utils/ci/install_cargo_web.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+
+set -euo pipefail
+IFS=$'\n\t'
+
+CARGO_WEB_RELEASE=$(curl -L -s -H 'Accept: application/json' https://github.com/koute/cargo-web/releases/latest)
+CARGO_WEB_VERSION=$(echo $CARGO_WEB_RELEASE | sed -e 's/.*"tag_name":"\([^"]*\)".*/\1/')
+CARGO_WEB_URL="https://github.com/koute/cargo-web/releases/download/$CARGO_WEB_VERSION/cargo-web-x86_64-unknown-linux-gnu.gz"
+
+echo "Downloading cargo-web from: $CARGO_WEB_URL"
+curl -L $CARGO_WEB_URL | gzip -d > cargo-web
+chmod +x cargo-web
+
+mkdir -p ~/.cargo/bin
+mv cargo-web ~/.cargo/bin