So far free variables references in eval code are not statically
resolved. For example in
    function foo() { var x = 1; eval("y = x"); }
the variable x will get mode DYNAMIC and y will get mode DYNAMIC_GLOBAL,
i.e. free variable references trigger dynamic lookups with a fast case
handling for global variables.

The CL introduces static resolution of free variables references in eval
code. If possible variable references are resolved to bindings belonging to
outer scopes of the eval call site.

This is achieved by deserializing the outer scope chain using
Scope::DeserializeScopeChain prior to parsing the eval code similar to lazy
parsing of functions. The existing code for variable resolution is used,
however resolution starts at the first outer unresolved scope instead of
always starting at the root of the scope tree.

This is a prerequisite for statically checking validity of assignments in
the extended code as specified by the current ES.next draft which will be
introduced by a subsequent CL. More specifically section 11.13 of revision 4
of the ES.next draft reads:
* It is a Syntax Error if the AssignmentExpression is contained in extended
  code and the LeftHandSideExpression is an Identifier that does not
  statically resolve to a declarative environment record binding or if the
  resolved binding is an immutable binding.

TEST=existing tests in mjsunit

Review URL: http://codereview.chromium.org/8508052

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9999 ce2b1a6d-e550-0410-aec6-3dcde31c8c00