node: don't malloc in FromConstructorTemplate

* allocate space for argv on the stack
* move the declaration to node_internals.h
typed arrays: make call-as-function work for ctors

Turn call-as-function calls into constructor calls. Makes the following
snippet work:

  var buf = ArrayBuffer(32);  // no 'new' but does the right thing
fs: fix immediate WriteStream#end()

Fix an exception that was raised when the WriteStream was closed
immediately after creating it:

  TypeError: Cannot read property 'fd' of undefined
      at WriteStream.close (fs.js:1537:18)
      <snip>

Avoid the TypeError and make sure the file descriptor is closed.

Fixes #4745.