Remove "prefer spread" option in ESLint.

This removes the “prefer spread” option which prefers
the (…args) syntax over using Array.prototype.apply. This
however is part of ES6 syntax and is incompatible with
IE*, Opera*, < Safari 8; and old Chrome, FF versions.

.eslintrc.json

@@ -135,7 +135,6 @@
         "no-new-func": "error",
         "space-before-function-paren": ["error", { "anonymous": "always", "named": "never", "asyncArrow": "always" }],
         "no-param-reassign": 0,
-        "prefer-spread": "error",
         "arrow-spacing": ["error", { "before": true, "after": true }],
         "no-alert": 2,
         "no-array-constructor": 2,