Revert of [strong] checking of this & super in constructors

src/messages.js

Index: src/messages.js
diff --git a/src/messages.js b/src/messages.js
index f50e8e7f6d444bcd82351ae1f9082f16f33fac0a..04e107dfdc86482f9444a9f99d0ac37952e86a11 100644
--- a/src/messages.js
+++ b/src/messages.js
@@ -143,11 +143,9 @@
   strong_unbound_global:         ["In strong mode, using an undeclared global variable '", "%0", "' is not allowed"],
   strong_super_call_missing:     ["In strong mode, invoking the super constructor in a subclass is required"],
   strong_super_call_duplicate:   ["In strong mode, invoking the super constructor multiple times is deprecated"],
-  strong_super_call_misplaced:   ["In strong mode, the super constructor must be invoked before any assignment to 'this'"],
-  strong_constructor_super:      ["In strong mode, 'super' can only be used to invoke the super constructor, and cannot be nested inside another statement or expression"],
-  strong_constructor_this:       ["In strong mode, 'this' can only be used to initialize properties, and cannot be nested inside another statement or expression"],
+  strong_super_call_nested:      ["In strong mode, invoking the super constructor nested inside another statement or expression is deprecated"],
   strong_constructor_return_value: ["In strong mode, returning a value from a constructor is deprecated"],
-  strong_constructor_return_misplaced: ["In strong mode, returning from a constructor before its super constructor invocation or all assignments to 'this' is deprecated"],
+  strong_constructor_return_misplaced: ["In strong mode, returning from a constructor before its super constructor invocation is deprecated"],
   sloppy_lexical:                ["Block-scoped declarations (let, const, function, class) not yet supported outside strict mode"],
   malformed_arrow_function_parameter_list: ["Malformed arrow function parameter list"],
   cant_prevent_ext_external_array_elements: ["Cannot prevent extension of an object with external array elements"],