e4ab45aa65
UnlinkedConstOperation.length is used not only if we can prove that the target is a StringLiteral (and actually we cannot encode it as a reference). The new ReferenceKind.length was added - it is used to encode reference to the the only instance property we support - 'length'. R=paulberry@google.com BUG= Review URL: https://codereview.chromium.org/1642483002 .