Upgrade to babel@7 and support TypeScript

See matrix-org/matrix-react-sdk#3292

.babelrc

@@ -1,15 +1,23 @@
 {
-    "presets": ["es2015"],
-    "plugins": [
-        "transform-class-properties",
-
-        // this transforms async functions into generator functions, which
-        // are then made to use the regenerator module by babel's
-        // transform-regnerator plugin (which is enabled by es2015).
-        "transform-async-to-bluebird",
-
-        // This makes sure that the regenerator runtime is available to
-        // the transpiled code.
-        "transform-runtime",
+    "presets": [
+        ["@babel/preset-env", {
+            "targets": {
+                "browsers": ["last 2 versions"],
+                "node": 10
+            },
+            "modules": "commonjs"
+        }],
+        "@babel/preset-typescript"
     ],
+    "plugins": [
+        "@babel/plugin-proposal-numeric-separator",
+        "@babel/plugin-proposal-class-properties",
+        "@babel/plugin-proposal-object-rest-spread",
+        "@babel/plugin-syntax-dynamic-import",
+        ["@babel/plugin-transform-async-to-generator", {
+            "module": "bluebird",
+            "method": "coroutine"
+        }],
+        "@babel/plugin-transform-runtime"
+    ]
 }

package.json

@@ -4,17 +4,17 @@
   "description": "Matrix Client-Server SDK for Javascript",
   "main": "index.js",
   "scripts": {
-    "test:build": "babel -s -d specbuild spec",
+    "test:build": "babel spec -s -d specbuild --verbose --extensions \".ts,.js\"",
     "test:run": "istanbul cover --report text --report cobertura --config .istanbul.yml -i \"lib/**/*.js\" node_modules/mocha/bin/_mocha -- --recursive specbuild --colors --reporter mocha-jenkins-reporter --reporter-options junit_report_path=reports/test-results.xml",
     "test:watch": "mocha --watch --compilers js:babel-core/register --recursive spec --colors",
     "test": "yarn test:build && yarn test:run",
     "check": "yarn test:build && _mocha --recursive specbuild --colors",
-    "gendoc": "babel --no-babelrc --plugins transform-class-properties -d .jsdocbuild src && jsdoc -r .jsdocbuild -P package.json -R README.md -d .jsdoc",
+    "gendoc": "babel src --no-babelrc --plugins @babel/plugin-proposal-class-properties -d .jsdocbuild --verbose --extensions \".ts,.js\" && jsdoc -r .jsdocbuild -P package.json -R README.md -d .jsdoc",
     "start": "yarn start:init && yarn start:watch",
-    "start:watch": "babel -s -w --skip-initial-build -d lib src",
-    "start:init": "babel -s -d lib src",
+    "start:watch": "babel src -s -w --skip-initial-build -d lib --verbose --extensions \".ts,.js\"",
+    "start:init": "babel src -s -d lib --verbose --extensions \".ts,.js\"",
     "clean": "rimraf lib dist",
-    "build": "babel -s -d lib src && rimraf dist && mkdir dist && browserify -d browser-index.js | exorcist dist/browser-matrix.js.map > dist/browser-matrix.js && terser -c -m -o dist/browser-matrix.min.js --source-map \"content='dist/browser-matrix.js.map'\" dist/browser-matrix.js",
+    "build": "babel src -s -d lib --verbose --extensions \".ts,.js\" && rimraf dist && mkdir dist && browserify -d browser-index.js | exorcist dist/browser-matrix.js.map > dist/browser-matrix.js && terser -c -m -o dist/browser-matrix.min.js --source-map \"content='dist/browser-matrix.js.map'\" dist/browser-matrix.js",
     "dist": "yarn build",
     "watch": "watchify -d browser-index.js -o 'exorcist dist/browser-matrix.js.map > dist/browser-matrix.js' -v",
     "lint": "eslint --max-warnings 101 src spec",
@@ -53,8 +53,7 @@
   ],
   "dependencies": {
     "another-json": "^0.2.0",
-    "babel-runtime": "^6.26.0",
-    "bluebird": "^3.5.0",
+    "bluebird": "^3.5.5",
     "browser-request": "^0.3.3",
     "bs58": "^4.0.1",
     "content-type": "^1.0.2",
@@ -64,12 +63,18 @@
     "unhomoglyph": "^1.0.2"
   },
   "devDependencies": {
-    "babel-cli": "^6.18.0",
+    "@babel/cli": "^7.5.5",
+    "@babel/core": "^7.5.5",
+    "@babel/plugin-proposal-class-properties": "^7.5.5",
+    "@babel/plugin-proposal-numeric-separator": "^7.2.0",
+    "@babel/plugin-proposal-object-rest-spread": "^7.5.5",
+    "@babel/plugin-syntax-dynamic-import": "^7.2.0",
+    "@babel/plugin-transform-async-to-generator": "^7.5.0",
+    "@babel/plugin-transform-runtime": "^7.5.5",
+    "@babel/preset-env": "^7.5.5",
+    "@babel/preset-typescript": "^7.3.3",
+    "@babel/runtime": "^7.5.5",
     "babel-eslint": "^10.0.1",
-    "babel-plugin-transform-async-to-bluebird": "^1.1.1",
-    "babel-plugin-transform-class-properties": "^6.24.1",
-    "babel-plugin-transform-runtime": "^6.23.0",
-    "babel-preset-es2015": "^6.18.0",
     "browserify": "^16.2.3",
     "browserify-shim": "^3.8.13",
     "eslint": "^5.12.0",
@@ -88,6 +93,7 @@
     "source-map-support": "^0.4.11",
     "sourceify": "^0.1.0",
     "terser": "^4.0.0",
+    "typescript": "^3.5.3",
     "watchify": "^3.11.1"
   },
   "browserify": {