navbar: Remove unnecessary "search_icon" styles.
navbar: Remove unnecessary "search_icon" styles.

This change corrects a bug that caused firefox to render the width
(and hence margin and position) of search_closed differently.

synicalsyntax/zulip,brainwane/zulip,showell/zulip,timabbott/zulip,punchagan/zulip,brainwane/zulip,shubhamdhama/zulip,andersk/zulip,showell/zulip,eeshangarg/zulip,hackerkid/zulip,zulip/zulip,kou/zulip,synicalsyntax/zulip,kou/zulip,shubhamdhama/zulip,synicalsyntax/zulip,hackerkid/zulip,eeshangarg/zulip,punchagan/zulip,showell/zulip,rht/zulip,punchagan/zulip,brainwane/zulip,shubhamdhama/zulip,timabbott/zulip,kou/zulip,eeshangarg/zulip,andersk/zulip,timabbott/zulip,andersk/zulip,zulip/zulip,kou/zulip,synicalsyntax/zulip,showell/zulip,rht/zulip,rht/zulip,showell/zulip,rht/zulip,punchagan/zulip,punchagan/zulip,brainwane/zulip,brainwane/zulip,synicalsyntax/zulip,zulip/zulip,synicalsyntax/zulip,hackerkid/zulip,eeshangarg/zulip,kou/zulip,eeshangarg/zulip,synicalsyntax/zulip,hackerkid/zulip,shubhamdhama/zulip,shubhamdhama/zulip,hackerkid/zulip,timabbott/zulip,punchagan/zulip,timabbott/zulip,brainwane/zulip,brainwane/zulip,zulip/zulip,timabbott/zulip,eeshangarg/zulip,andersk/zulip,hackerkid/zulip,rht/zulip,andersk/zulip,showell/zulip,eeshangarg/zulip,shubhamdhama/zulip,zulip/zulip,hackerkid/zulip,kou/zulip,rht/zulip,kou/zulip,shubhamdhama/zulip,timabbott/zulip,punchagan/zulip,zulip/zulip,andersk/zulip,andersk/zulip,zulip/zulip,showell/zulip,rht/zulip