attempt to always minify CSS before autoprefixing.

gulpfile.js

@@ -2,7 +2,6 @@ var path = require('path');
 var webserver = require('gulp-webserver');
 var _ = require('underscore');
 var gulp = require('gulp');
-var gulpif = require('gulp-if');
 var gutil = require('gulp-util');
 var s3 = require('gulp-s3');
 var gzip = require('gulp-gzip');
@@ -115,12 +114,15 @@ gulp.task('less', function() {
       paths: [path.join(__dirname, 'less')],
       filename: 'styles.css'
     }))
-    .pipe(gulpif(process.env.LESS_AUTOPREFIXER != 'off', autoprefixer({
+    // We explicitly want to minify the CSS even in development
+    // environments because otherwise sourcemaps won't work.
+    // https://github.com/mozilla/teach.webmaker.org/issues/413
+    .pipe(cssmin())
+    .pipe(autoprefixer({
       browsers: ['last 2 versions'],
       cascade: false,
       remove: true
-    })))
-    .pipe(gulpif(process.env.NODE_ENV === 'production', cssmin()))
+    }))
     .pipe(rename('styles.css'))
     .pipe(sourcemaps.write('./'))
     .pipe(gulp.dest('./dist'));

package.json

@@ -9,7 +9,6 @@
     "gulp": "^3.8.11",
     "gulp-autoprefixer": "^2.1.0",
     "gulp-gzip": "^1.0.0",
-    "gulp-if": "^1.2.5",
     "gulp-jsbeautify": "^0.1.1",
     "gulp-jscs": "^1.4.0",
     "gulp-jshint": "^1.9.2",