Add flow typechecking infrastructure (#3397)

* Add unflowify to build process

* Use "flow-bin" rather than "flow"

* Add "flow-remove-types" to render & query tests

* Simplified diff

* Upgrade flow-bin version

.eslintrc

@@ -1,5 +1,12 @@
 {
   "extends": "mourner",
+  "parser": "babel-eslint",
+  "parserOptions": {
+    "sourceType": "script",
+  },
+  "plugins": [
+    "flowtype"
+  ],
   "rules": {
     "array-bracket-spacing": "off",
     "block-scoped-var": "error",

.flowconfig

@@ -0,0 +1,11 @@
+[ignore]
+
+.*/node_modules/.*
+
+[include]
+
+[libs]
+
+./interfaces/
+
+[options]

interfaces/mapbox-gl-js-test.js

@@ -0,0 +1,4 @@
+declare module "mapbox-gl-js-test" {
+    declare type CreateTest = (name: string, body: (test: CreateTest) => void) => void;
+    declare var exports: CreateTest;
+}

interfaces/point-geometry.js

@@ -0,0 +1,40 @@
+declare module "point-geometry" {
+    declare class Point {
+        x: number;
+        y: number;
+        clone(): Point;
+        add(point: Point): Point;
+        sub(point: Point): Point;
+        multByPoint(point: Point): Point;
+        divByPoint(point: Point): Point;
+        mult(k: number): Point;
+        div(k: number): Point;
+        rotate(angle: number): Point;
+        rotateAround(angle: number, point: Point): Point;
+        matMult(matrix: [number, number, number, number]): Point;
+        unit(): Point;
+        perp(): Point;
+        round(): Point;
+        mag(): number;
+        equals(point: Point): boolean;
+        dist(point: Point): number;
+        distSqr(point: Point): number;
+        angle(): number;
+        angleTo(point: Point): number;
+        angleWith(point: Point): number;
+        angleWithSep(x: number, y: number): number;
+        _matMult(matrix: [number, number, number, number]): Point;
+        _add(point: Point): Point;
+        _sub(point: Point): Point;
+        _mult(k: number): Point;
+        _div(k: number): Point;
+        _multByPoint(point: Point): Point;
+        _divByPoint(point: Point): Point;
+        _unit(): Point;
+        _perp(): Point;
+        _rotate(angle: number): Point;
+        _rotateAround(angle: number, point: Point): Point;
+        _round(): Point;
+    }
+    declare var exports: typeof Point;
+}

interfaces/unitbezier.js

@@ -0,0 +1,11 @@
+declare module "unitbezier" {
+    declare class UnitBezier {
+        constructor(p1x: number, p1y: number, p2x: number, p2y: number): UnitBezier;
+        sampleCurveX(t: number): number;
+        sampleCurveY(t: number): number;
+        sampleCurveDerivativeX(t: number): number;
+        solveCurveX(t: number): number;
+        solve(x: number, epsilon?: number): number;
+    }
+    declare var exports: typeof UnitBezier;
+}

js/style/parse_color.js

@@ -8,7 +8,7 @@ const cache = {};
 
 module.exports = function parseColor(input) {
 
-    if (StyleFunction.isFunctionDefinition(input)) {
+    if (input && StyleFunction.isFunctionDefinition(input)) {
 
         if (!input.stops) return input;
         else return util.extend({}, input, {