How to prevent Command-I/Command-Shift-I from opening Mac Mail when in browser

This is a known “bug” which I don’t know if Apple will ever consider a bug.

The problem is that the list of browsers is generated “dynamically” each time you click on it (or at least the 1st time after Safari has been launched); the reasoning behind this is that different users will have a different set of browsers, so the list cannot be hardcoded. So given the above, the shortcut fails to work until the list has been “generated” by Safari. This occurs when you display the menu.

A possible solution would be to use Automator and create a service that opens the current safari page onto Chrome. But that’s beyond the scope of this answer.

TLDR version: There’s nothing you can do other than file a bug report at Apple if you want to stick with the same shortcut technique. Alternatives involve Automator.

I'd make a little AppleScript that does this:

on GetDefaultWebBrowser()
    set _scpt to "export VERSIONER_PERL_PREFER_32_BIT=yes; " & "perl -MMac::InternetConfig -le " & "'print +(GetICHelper \"http\")[1]'"
    return (do shell script _scpt)
end GetDefaultWebBrowser
do shell script "open -a \"" & GetDefaultWebBrowser() & "\""

Replace the URL (in quotes) with your homepage. The rest of the code serves to figure out what your default browser is, and make it the active application. That part lifted from a Daring Fireball article.

Save it as an app called Browser and put it somewhere. Once Spotlight indexes it, you can type Browser in and hit enter. This will open the URL in your default browser.

Directions:

Open AppleScript Editor from your Applications/Utilities folder (if you have older than 10.6, it will be Script Editor in your Applications folder). Paste that line in. Go to File-> Save As. Set the File Format: menu to Application. Choose a location and save.