Fix menu layout issues
Fix menu layout issues

Fixes issues #561, #559, #557 by reverting back to iron-flex-layout
version 1.2.1, version 1.2.2 causes this problem. Still

Fixes layout issues for Chrome, Firefox and Safari, but not IE 11 or
Edge (#550).

alexpaluzzi/polymer-starter-kit,mtusk/polymer-starter-kit,FaellCarvalho/Geo-Location,victorgb6/id-questionary,grebett/polymer-starter-kit,abdonrd/polymer-starter-kit,StartPolymer/polymer-starter-kit,Negashev/negash.ru,alexpaluzzi/polymer-starter-kit,gick/reveries-project,trendystore/store,stefanoantonel/ecofit,Ex-ante-Labs/pivot-ahead,stefanoantonel/ecofit,Ex-ante-Labs/pivot-ahead,JnJSW/dttdata,markovuksanovic/polymer-starter-kit,JnJSW/dttdata,RoyKoh/Project-3,felixzapata/polymer-starter-kit,SB-Technology-Holdings-International/WateringWebClient,SB-Technology-Holdings-International/Water,klarkc/polymer-loopback-starter-kit,stephenzsy/charon-frontend,anthonybrown/polymer-starter-kit,flaiker/polymer-starter-kit,stefanoantonel/brainpower,victorgb6/id-questionary,andrefuller/PolymerTrailerViewer,SB-Technology-Holdings-International/WateringWebClient,SB-Technology-Holdings-International/Water,StartPolymer/polymer-starter-kit-plus,markovuksanovic/polymer-starter-kit,Negashev/negash.ru,michaetto/f16,gick/reveries-project,alexpaluzzi/polymer-starter-kit,gick/reveries-project,semafloor/semafloor-test-alpha,lordoftheflies/mlm-portal,victorgb6/id-questionary,Ex-ante-Labs/shopper.ninja,trendystore/store,gertcuykens/polymer-starter-kit,gick/mobile-polymer-starter-2,mtusk/polymer-starter-kit,felixzapata/polymer-starter-kit,stephenzsy/charon-frontend,semafloor/semafloor-test-alpha,lordoftheflies/mlm-portal,michaetto/f16,RoyKoh/Project-3,markovuksanovic/polymer-starter-kit,FaellCarvalho/Geo-Location,felixzapata/polymer-starter-kit,Sykkro/penny-web,plusCubed/pluscubed-site,gertcuykens/polymer-starter-kit,Ex-ante-Labs/shopper.ninja,gick/mobile-polymer-starter-2,plusCubed/pluscubed-site,Serious-Rage/poligomy,SB-Technology-Holdings-International/WateringWebClient,stefanoantonel/brainpower,flaiker/polymer-starter-kit,Negashev/negash.ru,RoyKoh/Project-3,stefanoantonel/ecofit,SB-Technology-Holdings-International/Water,klarkc/polymer-loopback-starter-kit,Serious-Rage/poligomy,SB-Technology-Holdings-International/Water,lordoftheflies/mlm-portal,StartPolymer/polymer-starter-kit-plus,andrefuller/PolymerTrailerViewer,gick/mobile-polymer-starter-2,michaetto/f16,StartPolymer/polymer-starter-kit,klarkc/polymer-loopback-starter-kit,andrefuller/PolymerTrailerViewer,grebett/polymer-starter-kit,JnJSW/dttdata,anthonybrown/polymer-starter-kit,SB-Technology-Holdings-International/WateringWebClient,grebett/polymer-starter-kit,SB-Technology-Holdings-International/Water,trendystore/store,Sykkro/penny-web,FaellCarvalho/Geo-Location,Serious-Rage/poligomy,abdonrd/polymer-starter-kit,gertcuykens/polymer-starter-kit,Sykkro/penny-web,stephenzsy/charon-frontend,semafloor/semafloor-test-alpha