Fix strict mode when testing with PhantomJS 1.x.
Fix strict mode when testing with PhantomJS 1.x.

PhantonJS 1.x (and old versions of webkit, Safari, etc) don't properly
handle "use strict" directives if they are nested in functions more than
two deep.  Add a top-level "use strict" inside the first nested function
scope in order to prevent this bug from affecting core-js.

zloirock/core-js,synaptek/core-js,ErikBaath/core-js,zloirock/core-js,eteeselink/core-js,synaptek/core-js,jacobangel/core-js,ErikBaath/core-js,vjeux/core-js,eteeselink/core-js,abucur/core-js,abucur/core-js,zpao/core-js,jacobangel/core-js,zpao/core-js,vjeux/core-js