Visual Studio - Format on Enter no longer removes extra whitespace

[jessetrinity]

TypeScript Version:
typescript@3.3.0-dev.20181130

Search Terms:
formatting whitespace

Expected behavior:
Format on Enter previously removed extra whitespace inserted after the indentation on the empty line below var bar;. Caret represents the termination of whitespace on the previous line.

function foo()
{
    var bar;
    
    ^
}

Actual behavior:

Format on Enter no longer removes extra whitespace.

function foo()
{
    var bar;
        
        ^
}

Similar behavior is observed for non-empty lines.
Expected:

var foo;
        ^

Actual:

var foo;     
            ^

Related Issues:
Introduced by #27978

[minestarks]

@sandersn This is blocking our tests and I believe it exists in 3.2 which will ship with VS. My understanding is it causes a visible formatting issue in VS. Would you prioritize it accordingly?

[sandersn]

Here's a fourslash repro:

/// <reference path="fourslash.ts" />
////function foo()
////{
////    var bar;
////    /*1*/
////}
goTo.marker('1')
edit.insertLine("");
verify.currentFileContentIs(`function foo()
{
    var bar;


}`);

The two whitespace-only lines should both have 0 spaces. After #27978 merged, the first one still has 4 spaces.

[sandersn]

Selectively reverting #27978 shows that the regression was introduced by the change in trimTrailingWhitespacesForRemainingRange.