Keep natives source code in external strings instead of putting...

Keep natives source code in external strings instead of putting
it in regular flat strings that are part of the snapshot.
After this change we don't need libraries-empty.cc any more.  In
this change libraries-empty.cc is just a the same as libraries.cc
and the scons build builds it but does not use it.  We can move
in stages to a situation where it is not generated at all for all
the build systems that we have.

[Mads Ager (chromium), 2009-11-05 13:35:30]

LGTM

Does it lint? :-)

http://codereview.chromium.org/360050/diff/1/6
File src/bootstrapper.cc (right):

http://codereview.chromium.org/360050/diff/1/6#newcode104
Line 104: new
NativesExternalStringResource(Natives::GetScriptSource(index).start());
Line too long?

Do we ever delete these?  We should do something to eventually delete them. 
Otherwise we will get valgrind complaints.

http://codereview.chromium.org/360050/diff/1/6#newcode105
Line 105: Handle<String> source_code =
Factory::NewExternalStringFromAscii(resource);
Line too long?

http://codereview.chromium.org/360050/diff/1/5
File src/objects.cc (right):

http://codereview.chromium.org/360050/diff/1/5#newcode1143
Line 1143:
reinterpret_cast<ExternalAsciiString*>(this)->ExternalAsciiStringIterateBody(v);
Long lines?

http://codereview.chromium.org/360050/diff/1/5#newcode4413
Line 4413:
v->VisitExternalAsciiString(reinterpret_cast<Resource**>(FIELD_ADDR(this,
kResourceOffset)));
Long lines!

http://codereview.chromium.org/360050/diff/1/9
File src/serialize.cc (right):

http://codereview.chromium.org/360050/diff/1/9#newcode2066
Line 2066: new
NativesExternalStringResource(Natives::GetScriptSource(index).start());
Long line?

http://codereview.chromium.org/360050/diff/1/9#newcode2317
Line 2317: ExternalAsciiString* string =
reinterpret_cast<ExternalAsciiString*>(source);
Long line?