fix(copy): angular copy should throw exception when source and destin…

[m-amr]

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

bug

What is the current behavior? (You can also link to an open issue here)
#15444

What is the new behavior (if this is a feature change)?
when angular copy source and destination are not the same type, it throw an exception

Does this PR introduce a breaking change?

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:

…ation are not the same type

Closes #15444

[m-amr]

This will require removing some test cases like

 it('should clear destination arrays correctly when source is non-array', function() {
  expect(copy(null, [1,2,3])).toEqual([]);
  expect(copy(undefined, [1,2,3])).toEqual([]);
  expect(copy({0: 1, 1: 2}, [1,2,3])).toEqual([1,2]);
  expect(copy(new Date(), [1,2,3])).toEqual([]);
  expect(copy(/a/, [1,2,3])).toEqual([]);
  expect(copy(true, [1,2,3])).toEqual([]);
});

it('should clear destination objects correctly when source is non-array', function() {
  expect(copy(null, {0:1,1:2,2:3})).toEqual({});
  expect(copy(undefined, {0:1,1:2,2:3})).toEqual({});
  expect(copy(new Date(), {0:1,1:2,2:3})).toEqual({});
  expect(copy(/a/, {0:1,1:2,2:3})).toEqual({});
  expect(copy(true, {0:1,1:2,2:3})).toEqual({});
});

Since that these cases will never happened because the source and destination must be the same type.
Is there is a reason to keep these cases ? they are useless now.

[gkalpak]

I am putting this in the Ice Box, as I don't think this change is appropriate (see #15444 (comment)).
I could get cnvinced otherwise thougg (if there is a compelling usecase).