Partial Application Syntax: Stage 1 (#9343)

* add partial application syntax and some tests

* remove unnecessary error message and hasPartial function from parseNewArguments

* add types for PartialExpression

* Update the tests

* rename PartialExpression to Partial

* move Partial from expressions to types and rename to ArgumentPlaceholder

* add tests for ArgumentPlaceholder in babel-generator

* rename Partial to ArgumentPlaceholder

* update the tests

* remove alias from the type and undo changes in generated folder

* adds a nice error message

* better definition for the type

* auto-generated files

* update the conditional for allowPlaceholder message and tests

* update CallExpression definition to accept ArgumentPlaceholder

* change description

* clean up

* indent ArgumentPlaceholder entry and revert unwanted changes

packages/babel-plugin-syntax-partial-application/package.json

@@ -0,0 +1,23 @@
+{
+  "name": "@babel/plugin-syntax-partial-application",
+  "version": "7.2.0",
+  "description": "Allow parsing of partial application syntax",
+  "repository": "https://github.com/babel/babel/tree/master/packages/babel-plugin-syntax-partial-application",
+  "license": "MIT",
+  "publishConfig": {
+    "access": "public"
+  },
+  "main": "lib/index.js",
+  "keywords": [
+    "babel-plugin"
+  ],
+  "dependencies": {
+    "@babel/helper-plugin-utils": "^7.0.0"
+  },
+  "peerDependencies": {
+    "@babel/core": "^7.0.0-0"
+  },
+  "devDependencies": {
+    "@babel/core": "^7.2.0"
+  }
+}