Conversion of Less to ES6 w/ TypeScript type linting support (#3411)

* Update lebab conversion
* Updated rollup config
* All tests passing
* Proper dist files
* Fixed browsertest compilation, cleaned up comments
* Update dependencies
* Remove spread operator for Node 6
* Improved browser test setup
* Downgrade grunt-eslint to support Node 6
* Add console errors for unfinished Less promise
* Simplify in-browser plugin

.eslintignore

@@ -1,2 +1,5 @@
 Gruntfile.js
-test/browser/vendor/*
+dist/*
+tmp/*
+test/browser/vendor/*
+test/browser/less.min.js

.eslintrc.json

@@ -1,89 +1,71 @@
 {
-  "env": {
-    "node": true
-  },
-  "globals": {},
-
-  "rules": {
-    "no-eval": 2,
-    "no-use-before-define": [
-      2,
-      {
-        "functions": false
-      }
-    ],
-    "no-undef": 0,
-    "no-unused-vars": 1,
-    "no-caller": 2,
-    "no-eq-null": 1,
-    "guard-for-in": 2,
-    "no-implicit-coercion": [
-      2,
-      {
-        "boolean": false,
-        "string": true,
-        "number": true
-      }
-    ],
-    "no-with": 2,
-    "no-mixed-spaces-and-tabs": 2,
-    "no-multiple-empty-lines": 2,
-    "dot-location": [
-      2,
-      "property"
-    ],
-    "operator-linebreak": [
-      0,
-      "after"
-    ],
-    "keyword-spacing": [
-      2,
-      {}
-    ],
-    "space-unary-ops": [
-      2,
-      {
-        "words": false,
-        "nonwords": false
-      }
-    ],
-    "no-spaced-func": 2,
-    "space-before-function-paren": [
-      1,
-      {
-        "anonymous": "ignore",
-        "named": "never"
-      }
-    ],
-    "comma-dangle": [
-      2,
-      "never"
-    ],
-    "no-trailing-spaces": 0,
-    "max-len": [
-      2,
-      160
-    ],
-    "comma-style": [
-      2,
-      "last"
-    ],
-    "curly": [
-      2,
-      "all"
-    ],
-    "space-infix-ops": 2,
-    "spaced-comment": 1,
-    "space-before-blocks": [
-      2,
-      "always"
-    ],
-    "indent": [
-      2,
-      4,
-      {
-        "SwitchCase": 1
-      }
-    ]
-  }
+    "parser": "@typescript-eslint/parser",
+    "parserOptions": {
+        "ecmaVersion": 2018,
+        "sourceType": "module"
+    },
+    "plugins": ["@typescript-eslint"],
+    "env": {
+        "browser": true,
+        "node": true
+    },
+    "globals": {},
+    "rules": {
+        "no-eval": 2,
+        "no-use-before-define": [
+            2,
+            {
+                "functions": false
+            }
+        ],
+        "no-undef": 0,
+        "no-unused-vars": 1,
+        "no-caller": 2,
+        "no-eq-null": 1,
+        "guard-for-in": 2,
+        "no-implicit-coercion": [
+            2,
+            {
+                "boolean": false,
+                "string": true,
+                "number": true
+            }
+        ],
+        "no-with": 2,
+        "no-mixed-spaces-and-tabs": 2,
+        "no-multiple-empty-lines": 2,
+        "dot-location": [2, "property"],
+        "operator-linebreak": [0, "after"],
+        "keyword-spacing": [2, {}],
+        "space-unary-ops": [
+            2,
+            {
+                "words": false,
+                "nonwords": false
+            }
+        ],
+        "no-spaced-func": 2,
+        "space-before-function-paren": [
+            1,
+            {
+                "anonymous": "ignore",
+                "named": "never"
+            }
+        ],
+        "comma-dangle": [2, "never"],
+        "no-trailing-spaces": 0,
+        "max-len": [2, 160],
+        "comma-style": [2, "last"],
+        "curly": [2, "all"],
+        "space-infix-ops": 2,
+        "spaced-comment": 1,
+        "space-before-blocks": [2, "always"],
+        "indent": [
+            2,
+            4,
+            {
+                "SwitchCase": 1
+            }
+        ]
+    }
 }

.gitignore

@@ -14,7 +14,8 @@ npm-debug.log
 
 # project-specific
 tmp
-test/browser/less.js
+test/browser/less.min.js
+test/browser/less.min.js.map
 test/sourcemaps/**/*.map
 test/sourcemaps/*.map
 test/sourcemaps/*.css

.npmignore

@@ -1,4 +1,6 @@
 .gitattributes
+.travis.yml
+appveyor.yml
 build/
 .grunt/
 benchmark/

.travis.yml

@@ -3,7 +3,8 @@ cache:
   directories:
     - travis-phantomjs
 node_js:
-  - "9"
+  - "12"
+  - "10"
   - "8"
   - "6"
 before_install: