Use strict. For real.

src/coffee-script.coffee

@@ -99,7 +99,10 @@ exports.eval = (code, options = {}) ->
       sandbox.module  = _module  = new Module(options.modulename || 'eval')
       sandbox.require = _require = (path) ->  Module._load path, _module, true
       _module.filename = sandbox.__filename
-      _require[r] = require[r] for r in Object.getOwnPropertyNames require when r isnt 'paths'
+      for r in Object.getOwnPropertyNames require when r isnt 'paths'
+        descriptor = Object.getOwnPropertyDescriptor require, r
+        continue unless descriptor.writable
+        _require[r] = require[r]
       # use the same hack node currently uses for their own REPL
       _require.paths = _module.paths = Module._nodeModulePaths process.cwd()
       _require.resolve = (request) -> Module._resolveFilename request, _module

src/nodes.coffee

@@ -261,7 +261,7 @@ exports.Block = class Block extends Base
       @expressions = rest
     code = @compileWithDeclarations o
     return code if o.bare
-    "#{prelude}(function() {\n#{code}\n}).call(this);\n"
+    "#{prelude}(function() {\n#{TAB}'use strict';\n#{code}\n}).call(this);\n"
 
   # Compile the expressions body for the contents of a function, with
   # declarations of all inner variables pushed up to the top.

test/function_invocation.coffee

@@ -305,10 +305,16 @@ test "Prefix unary assignment operators are allowed in parenless calls.", ->
   ok (func --val) is 5
 
 test "#855: execution context for `func arr...` should be `null`", ->
-  contextTest = -> eq @, if window? then window else global
+  contextTest = ->
+    if this is undefined
+      eq this, undefined
+    else if this is null
+      eq this, null
+    else
+      eq this, window ? global
   array = []
   contextTest array
-  contextTest.apply null, array
+  contextTest.apply undefined, array
   contextTest array...
 
 test "#904: Destructuring function arguments with same-named variables in scope", ->