Add private fields tests of early errors and small fix

src/class-fields/init-err-contains-boolean.case

-// Copyright (C) 2017 Valerie Young. All rights reserved.
-// This code is governed by the BSD license found in the LICENSE file.
-
-/*---
-desc: Syntax error if `arguments` used in class field
-info: |
-  Static Semantics: Early Errors
-
-    FieldDefinition:
-      PropertyNameInitializeropt
-
-    - It is a Syntax Error if ContainsArguments of Initializer is true.
-
-  Static Semantics: ContainsArguments
-    IdentifierReference : Identifier
-
-    1. If the StringValue of Identifier is "arguments", return true.
-    ...
-    For all other grammatical productions, recurse on all nonterminals. If any piece returns true, then return true. Otherwise return false.
-features: [class-fields]
-negative:
-  type: SyntaxError
-  phase: early
-template: initializer-error
----*/
-
-//- initializer
-arguments

src/class-fields/initializer-error/cls-decl-fields-static-private-name.template

+// Copyright (C) 2017 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-class-definitions-static-semantics-early-errors
+path: language/statements/class/fields-static-private-
+name: static PrivateName
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+class C {
+  static #x = /*{ initializer }*/;
+}

src/class-fields/initializer-error/cls-expr-fields-static-private-name.template

+// Copyright (C) 2017 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-class-definitions-static-semantics-early-errors
+path: language/expressions/class/fields-static-private-
+name: static PrivateName
+---*/
+
+throw "Test262: This statement should not be evaluated.";
+
+var C = class {
+  static #x = /*{ initializer }*/;
+}