Fix layout test and snapshot archive URLs by making them contain the builder  name too.
Fix layout test and snapshot archive URLs by making them contain the builder 
name too.

(Redone version of r74185 that works with lazily-evaluated property names)
Review URL: http://codereview.chromium.org/6474014

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@74543 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build