Added support for static private fields accessors and methods.

CONTRIBUTING.md

@@ -170,7 +170,7 @@ You can also use the [provided VS Code launch configuration](./.vscode/launch.te
 
 ## Adding a Test
 
-To add a new test case, add a `.ts` file in `tests\cases\compiler` with code that shows the your bug is now fixed, or your new feature now works.
+To add a new test case, add a `.ts` file in `tests\cases\compiler` with code that shows the bug is now fixed, or your new feature now works.
 
 These files support metadata tags in the format  `// @metaDataName: value`.
 The supported names and values are the same as those supported in the compiler itself, with the addition of the `fileName` flag.

src/compiler/binder.ts

@@ -3187,7 +3187,7 @@ namespace ts {
                 undefined;
             init = init && getRightMostAssignedExpression(init);
             if (init) {
-                const isPrototypeAssignment = isPrototypeAccess(isVariableDeclaration(node) ? node.name : isBinaryExpression(node) ? node.left : node);
+                const isPrototypeAssignment = isPrototypeAccess(isVariableDeclaration(node!) ? node.name : isBinaryExpression(node!) ? node.left : node!);
                 return !!getExpandoInitializer(isBinaryExpression(init) && (init.operatorToken.kind === SyntaxKind.BarBarToken || init.operatorToken.kind === SyntaxKind.QuestionQuestionToken) ? init.right : init, isPrototypeAssignment);
             }
             return false;