Since js_try can throw to its surrounding exception scope if it runs out
of space in the exception stack, we need to make sure to allocate
resources guarded by the try inside the try not outside it.
The temporary array we use for sorting cannot be seen by the GC, and that
violates the constraint that all js_Value values must always be reachable
from the stack or global environment.
Temporarily turning off the GC will let us use the temporary array for
fast sorting using qsort(), without tripping over this violation.
Don't distinguish lax mode code by pushing the global object.
Always push undefined and let the calling code promote an undefined
this to the global object instead.
The 'length' field of a function is used to fill in missing arguments
with undefined; this does not mesh well with functions that query for
missing arguments using js_gettop. Set their lengths to 0 instead.
Revert 'add context and flag argument to js_newstate' commit.
The context argument just adds clutter. The flag which was intended
for JS_DEBUG and/or JS_STRICT shouldn't be necessary.
js_newcfunction and js_newcconstructor need an extra argument, the
name of the function to use in stack traces.
js_newuserdata(J, tag, ptr) creates a userdata object, wrapping the ptr.
It takes the prototype for the new object from the top of the stack, just
like js_newcconstructor does.
js_touserdata(J, tag, idx) extracts the userdata pointer. Throws a
TypeError if the object is not a userdata object with a matching tag.
js_isuserdata(J, tag, idx) checks if a value on the stack is a userdata
object with a matching tag.
