Discovered IE11 has trouble parsing proxy.pac if large amount of whitespace (17 chars) appended at end of "if" statement

Connected a Win8.1 tablet running IE11 to our Juniper VPN (which has recently provided work around to support http://127.0.0.1:port/proxy.pac  address instead of local file reference of instantproxy.pac using file://)

We had an "If" statement in the middle of our proxy.pac which had whitespace padded at the end of the statement: 

if (host=="a.b.c.d")                 <CR/LF>return "DIRECT";<CR/LF>

The problem is that IE11 was then ignoring all subsequent lines in proxy.pac that followed the line with the 17 characters of  whitespace padding.

Is this a new bug introduced with IE11?

Our solution was to remove the extraneous whitespace at the end of the line, and the problem was resolved.

Why would IE11 have trouble with this whitespace added at the end of an "if" statement?