Enforce balanced block comments

See standard/standard#572

eslintrc.json

@@ -135,7 +135,7 @@
     "space-in-parens": [2, "never"],
     "space-infix-ops": 2,
     "space-unary-ops": [2, { "words": true, "nonwords": false }],
-    "spaced-comment": [2, "always", { "markers": ["global", "globals", "eslint", "eslint-disable", "*package", "!", ","] }],
+    "spaced-comment": [2, "always", { "line": { "markers": ["eslint", "eslint-disable", "*package", "!", ","] }, "block": { "balanced": true, "markers": ["*package", "!", ","], "exceptions": ["*"] } }],
     "template-curly-spacing": [2, "never"],
     "unicode-bom": [2, "never"],
     "use-isnan": 2,