AddBoundMethod, in i18n.js, returns functions all of which share the
same backing SharedFunctionInfo, which means that its calls to
InstallGetter were causing all such functions to have a single name
(that of the last caller, "get breakType").

This patch skips calling InstallGetter and instead directly calls
%DefineGetterPropertyUnchecked, which itself sets the name property
on the JSFunction instance (it knows how to do this in order to handle
getters that have computed property names).

Also takes care of a TODO having to do with the inner boundMethod:
its name is now made empty, by using a new macro that gets around
ES2015's function name inference.

Finally, removes a redundant %FunctionRemovePrototype: arrow functions
have no prototypes to begin with.

R=littledan@chromium.org
BUG=v8:4778

Review-Url: https://codereview.chromium.org/2109223002
Cr-Commit-Position: refs/heads/master@{#37459}