ES6 modules & Rollup (Leaflet#4989)

* WIP ES6 modules & rollup

* WIP ES6 modules & rollup 2

* WIP ES6 modules & rollup 3

* WIP ES6 modules Browser

* WIP ES6 module fixes

* WIP ES6 modules: simpler browser exports

* WIP ES6: refactor CRS/Projection modules, CRS obj -> CRS.Base

* get rid of unnecessary index.js

* WIP ES6 modules, dom events and stuff

* Make linter happy, rollup to dist/

* revert to CRS namespace/class for now

* WIP rollup: export more stuff

* export controls

* rollup: export Layer

* rollup: export DomEvent

* rollup: export more layer types

* rollup: export Popup/Tooltip

* WIP: ES6-ify marker, icon, domutil, draggable.

* ES6-ify gridlayer, tilelayer.

* ES6-ify: Tweak imports-exports, code is now runnable!!

* ES6-ify: Fix scope in some DomUtils

* ES6-ify: Path, fix Popup

* ES6-ify: Lint & cleanup

* ES6-ify map handlers, more linting

* ES6-ify: Icon.Default namespacing

* ES6-ify: Renderers, CircleMarker

* ES6-ify: Circle, Polyline, LineUtil

* ES6-ify: Polygon, Rectangle, LineUtil, PolyUtil, linting

* ES6-ify: SVG.VML

* ES6-ify: DomEvent.Pointer, DomEvent.DoubleTap

* ES6-ify: Linting, make Karma play nice with Rollup

* ES6-ify: More work on fixing bits breaking some unit tests.

* ES6-ify: rollup the version number, fiddled with build scripts

* ES6-ify: Fiddle with test scripts

* ES6-ify: cleanup (refs to global L, imports from (DOM)Util), prevent cyclic loop on Map imports

* ES6-ify: More cleanup of (DOM)Util/Browser/DomEvent imports

* ES6ify: Use rollup's "legacy" option for ES3 (IE8) builds

* ES6-ify: Clean up build scripts, fix CONTRIBUTING.md instructions

* Typo

* ES6-ify: minor fixes and lefovers after rebasing on top of 1.0.2

* ES6-ify: upgrade to rollup 0.38 for proper IE8 builds, fix L.SVG.VML

* Make linter happy.

* ES6: Fixing typos and sxrew-ups after big rebase

* Fix symlink for debugging scripts

* ES6: Cleanup old build scripts

* ES6-ify: Update build system to include git rev in L.version

* ES6-ify: re-enable unit tests replacing L.Path with L.Polyline

* Export Path

* ES6ify: cleanup old banner file

* ES6-ify: whitespace in var declarations

* ES6-ify: Export toTransformation as L.transformation

* ES6-ify: cleanup L.transform exports

* ES6-ify: "import Util" in Transformation and SVG.VML

CONTRIBUTING.md

@@ -72,9 +72,11 @@ To set up the Leaflet build system, install Node then run the following commands
 npm install -g jake
 npm install
 ```
-
-You can build minified Leaflet by running `jake` (it will be built from source in the `dist` folder).
-For a custom build with selected components, open `build/build.html` in the browser and follow the instructions from there.
+or, if you prefer [`yarn`](https://yarnpkg.com/) over `npm`:
+```
+yarn install -g jake
+yarn install
+```
 
 ### Making Changes to Leaflet Source
 
@@ -96,6 +98,25 @@ Also, please make sure that you have [line endings configured properly](https://
 
 Happy coding!
 
+### Using RollupJS
+
+The source javascript code for Leaflet is a few dozen files, in the `src/` directory.
+But normally, Leaflet is loaded in a web browser as just one javascript file.
+
+In order to create this file, run `npm run-script rollup` or `yarn run rollup`.
+
+You'll find `dist/leaflet-src.js` and `dist/leaflet.js`. The difference is that
+`dist/leaflet-src.js` has sourcemaps and it's not uglified, so it's better for
+development. `dist/leaflet.js` is uglified and thus is smaller, so it's better
+for deployment.
+
+When developing (or bugfixing) core Leaflet functionalities, it's common to use
+the webpages in the `debug/` directory, and run the unit tests (`spec/index.html`)
+in a graphical browser. This requires regenerating the bundled files quickly.
+
+In order to do so, run `npm run-script watch` or `yarn run rollup`. This will keep
+on rebuilding the bundles whenever any source file changes.
+
 ## Running the Tests
 
 To run the tests from the command line,
@@ -158,7 +179,8 @@ code for every method, option or property there is a special code comment docume
 that feature. In order to edit the API documentation, just edit these comments in the
 source code.
 
-In order to generate the documentation, just run
+In order to generate the documentation, make sure that the development dependencies
+are installed (run either `npm install` or `yarn install`), then just run
 
 ```
 jake docs

Jakefile.js

@@ -12,9 +12,9 @@ To run the tests, run "jake test". To build the documentation, run "jake docs".
 For a custom build, open build/build.html in the browser and follow the instructions.
 */
 
-var build = require('./build/build.js'),
-    buildDocs = require('./build/docs'),
-    git = require('git-rev');
+var buildDocs = require('./build/docs'),
+    git = require('git-rev-sync'),
+    path = require('path');
 
 function hint(msg, args) {
 	return function () {
@@ -29,16 +29,14 @@ function hint(msg, args) {
 
 // Returns the version string in package.json, plus a semver build metadata if
 // this is not an official release
-function calculateVersion(officialRelease, callback) {
+function calculateVersion(officialRelease) {
 
 	var version = require('./package.json').version;
 
 	if (officialRelease) {
-		callback(version);
+		return version;
 	} else {
-		git.short(function(str) {
-			callback (version + '+' + str);
-		});
+		return version + '+' + git.short();
 	}
 }
 
@@ -48,16 +46,53 @@ task('lint', {async: true}, hint('Checking for JS errors...', 'src'));
 desc('Check Leaflet specs source for errors with ESLint');
 task('lintspec', {async: true}, hint('Checking for specs JS errors...', 'spec/suites'));
 
-desc('Combine and compress Leaflet source files');
-task('build', {async: true}, function (compsBase32, buildName, officialRelease) {
-	calculateVersion(officialRelease, function(v){
-		build.build(complete, v, compsBase32, buildName);
-	});
-});
-
 desc('Run PhantomJS tests');
 task('test', ['lint', 'lintspec'], {async: true}, function () {
-	build.test(complete);
+
+	var karma = require('karma'),
+	 testConfig = {configFile : path.join(__dirname, './spec/karma.conf.js')};
+
+	 testConfig.browsers = ['PhantomJSCustom'];
+
+	 function isArgv(optName) {
+		 return process.argv.indexOf(optName) !== -1;
+	 }
+
+	 if (isArgv('--chrome')) {
+		 testConfig.browsers.push('Chrome');
+	 }
+	 if (isArgv('--safari')) {
+		 testConfig.browsers.push('Safari');
+	 }
+	 if (isArgv('--ff')) {
+		 testConfig.browsers.push('Firefox');
+	 }
+	 if (isArgv('--ie')) {
+		 testConfig.browsers.push('IE');
+	 }
+
+	 if (isArgv('--cov')) {
+		 testConfig.preprocessors = {
+			 'src/**/*.js': 'coverage'
+		 };
+		 testConfig.coverageReporter = {
+			 type : 'html',
+	 dir : 'coverage/'
+		 };
+		 testConfig.reporters = ['coverage'];
+	 }
+
+	 console.log('Running tests...');
+
+	 var server = new karma.Server(testConfig, function(exitCode) {
+		 if (!exitCode) {
+			 console.log('\tTests ran successfully.\n');
+			 complete();
+		 } else {
+			 process.exit(exitCode);
+		 }
+	 });
+	 server.start();
 });
 
 desc('Build documentation');

bower.json

@@ -6,7 +6,7 @@
     "dist/leaflet.css",
     "dist/leaflet-src.js"
   ],
-   "ignore": [
+  "ignore": [
     ".*",
     "CHANGELOG.json",
     "FAQ.md",