V8intrinsic syntax plugin (#10148)

* feat: v8intrinsic syntax plugin

Implement V8 Intrinsic Syntax Extension. Here we check the execution branch inside the parseSubscript to make sure the V8IntrinsicIdentifier is immediately followed by a call expression.

* feat: disable combining placeholders and v8intrisic

per https://github.com/babel/babel/issues/10104#issuecomment-506950969

* test: add more error cases

* refactor: parse v8 intrinsic in parseExprAtom

This approach is identical to V8’s implementation. Move the test cases as the behaviour changes.

* fix: plugin-name typo

* test: add yield-expression test case

* feat: require startsExpr on modulo for v8intrinsic

* perf: skip eof and braceR check as they must return false

* Print V8IntrinsicIdentifier

* feat: add v8intrinsic to parser typings

* Add generated type helpers

* fix: incorrect type definition

* fix: allow V8IntrinsicIdentifier to be callee

packages/babel-parser/src/plugins/v8intrinsic.js

@@ -0,0 +1,32 @@
+import type Parser from "../parser";
+import { types as tt } from "../tokenizer/types";
+import * as N from "../types";
+
+export default (superClass: Class<Parser>): Class<Parser> =>
+  class extends superClass {
+    parseV8Intrinsic(): N.Expression {
+      if (this.match(tt.modulo)) {
+        const v8IntrinsicStart = this.state.start;
+        // let the `loc` of Identifier starts from `%`
+        const node = this.startNode();
+        this.eat(tt.modulo);
+        if (this.match(tt.name)) {
+          const name = this.parseIdentifierName(this.state.start);
+          const identifier = this.createIdentifier(node, name);
+          identifier.type = "V8IntrinsicIdentifier";
+          if (this.match(tt.parenL)) {
+            return identifier;
+          }
+        }
+        this.unexpected(v8IntrinsicStart);
+      }
+    }
+
+    /* ============================================================ *
+     * parser/expression.js                                         *
+     * ============================================================ */
+
+    parseExprAtom(): N.Expression {
+      return this.parseV8Intrinsic() || super.parseExprAtom(...arguments);
+    }
+  };