bottle: fix Ruby 1.8 breakage
bottle: fix Ruby 1.8 breakage

`OpenStruct` (of which `Tab` is a subclass) doesn't support subscripting
with square brackets. Use normal dot notation to restore compatibility.

nandub/brew,reitermarkus/brew,mahori/brew,vitorgalvao/brew,claui/brew,toonetown/homebrew,JCount/brew,sjackman/homebrew,reitermarkus/brew,gregory-nisbet/brew,claui/brew,Linuxbrew/brew,Homebrew/brew,rwhogg/brew,konqui/brew,EricFromCanada/brew,staticfloat/brew,DomT4/brew,palxex/brew,rwhogg/brew,muellermartin/dist,gregory-nisbet/brew,mahori/brew,bfontaine/brew,staticfloat/brew,tonyg/homebrew,tonyg/homebrew,Homebrew/brew,mgrimes/brew,sjackman/homebrew,sjackman/homebrew,mgrimes/brew,mgrimes/brew,alyssais/brew,Linuxbrew/brew,nandub/brew,maxim-belkin/brew,pseudocody/brew,reelsense/brew,muellermartin/dist,JCount/brew,EricFromCanada/brew,AnastasiaSulyagina/brew,ilovezfs/brew,toonetown/homebrew,alyssais/brew,Homebrew/brew,gordonmcshane/homebrew,AnastasiaSulyagina/brew,ilovezfs/brew,pseudocody/brew,DomT4/brew,MikeMcQuaid/brew,zmwangx/brew,palxex/brew,vitorgalvao/brew,reelsense/brew,toonetown/homebrew,jmsundar/brew,Linuxbrew/brew,aw1621107/brew,gordonmcshane/homebrew,hanxue/linuxbrew,amar-laksh/brew_sudo,mistydemeo/homebrew,alyssais/brew,nandub/brew,claui/brew,maxim-belkin/brew,hanxue/linuxbrew,amar-laksh/brew_sudo,bfontaine/brew,EricFromCanada/brew,jmsundar/brew,bfontaine/brew,gordonmcshane/homebrew,mistydemeo/homebrew,nandub/brew,Homebrew/brew,muellermartin/dist,vitorgalvao/brew,reitermarkus/brew,palxex/brew,JCount/brew,aw1621107/brew,vitorgalvao/brew,staticfloat/brew,zmwangx/brew,konqui/brew,rwhogg/brew,sjackman/homebrew,mahori/brew,pseudocody/brew,AnastasiaSulyagina/brew,DomT4/brew,claui/brew,jmsundar/brew,MikeMcQuaid/brew,ilovezfs/brew,tonyg/homebrew,konqui/brew,reitermarkus/brew,reelsense/brew,EricFromCanada/brew,zmwangx/brew,mahori/brew,MikeMcQuaid/brew,Linuxbrew/brew,JCount/brew,amar-laksh/brew_sudo,aw1621107/brew,DomT4/brew,maxim-belkin/brew,gregory-nisbet/brew,hanxue/linuxbrew,mistydemeo/homebrew,MikeMcQuaid/brew,konqui/brew