Simplify stack iterators implementation

In order to fix https://code.google.com/p/chromium/issues/detail?id=252097 I
need to change SafeStackTraceFrameIterator. Stack iterators hierarchy looks
excessively complicated and I'd like to flatten it a bit by removing some
intermediate classes. In particular there are two hierarchies sharing
JavaScriptFrameIteratorTemp<T> template for no good reason.

This change extracts some of JavaScriptFrameIteratorTemp functionality directly
into SafeStackTraceFrameIterator. This made it obvious that a few checks were
performed twice.

The rest of JavaScriptFrameIteratorTemp<T> is merged with
JavaScriptFrameIterator. Now that the class is not a template some of its
implementation is moved from frames-inl.h into frames.cc

So in this change I removed JavaScriptFrameIterator and
SafeJavaScriptFrameIterator. As the next step I'm going to merge
SafeStackFrameIterator into SafeStackTraceFrameIterator.

BUG=None
R=loislo@chromium.org, svenpanne@chromium.org

Review URL: https://codereview.chromium.org/16917004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15275 ce2b1a6d-e550-0410-aec6-3dcde31c8c00