fix($scope): fixes multiple root element error when there is a whites…

[renovatorruler]

What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
Bug fix

What is the current behavior? (You can also link to an open issue here)
If one tries to load a directive with a top-level comment angular throws an error
Error: [$compile:tplrt] Template for directive 'myDirective' must have exactly one root element
#15108

Does this PR introduce a breaking change?
No

Please check if the PR fulfills these requirements

• The commit message follows our guidelines: https://github.com/angular/angular.js/blob/master/CONTRIBUTING.md#commit-message-format
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

Other information:

fixes multiple root element error when there is a whitespace after a comment

Added new conditional for NODE_TYPE_TEXT inside removeComments method of $compile
Added corresponding unit tests.

Closes #15108

[Narretz]

This issue doesn't only happen with replace directives, but with any directive that has a comment node with whitespace around it. I think these two tests should be added:

            // comments are ok
            $templateCache.put('template.html', '<!-- oh hi --><div></div> \n');
            $compile('<p template></p>');
            $rootScope.$apply();
            expect($exceptionHandler.errors).toEqual([]);

            // white space around comments is ok
            $templateCache.put('template.html', '  <!-- oh hi -->  <div></div>  <!-- oh hi -->\n');
            $compile('<p template></p>');
            $rootScope.$apply();
            expect($exceptionHandler.errors).toEqual([]);

for the test it('should fail if replacing and template doesn\'t have a single root element'

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[renovatorruler]

@Narretz Added those tests

[Narretz]

@prashantpawar Sorry, you are right, it's all replace directives. It looks like these tests are duplicated in a few places.