* Turned all uses of 'const' into 'var'.
* Turned all uses of local 'function' into 'var'.
* Added a couple of missing toplevel 'var' declarations.

One consequence is that the properties on the builtin object  are no longer
non-writable, and I had to adapt one test. Is that a problem?

Unfortunately, we cannot actually switch the library scripts to strict mode
by default, because that makes observable things like poisoned .caller properties
for library functions.

Also removed dead flag code in Compiler::Compile.

R=yangguo@chromium.org
BUG=
TEST=

Review URL: https://chromiumcodereview.appspot.com/9415010

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10758 ce2b1a6d-e550-0410-aec6-3dcde31c8c00