remove unneeded string cast
remove string casts from loader which was done for template reference objects, but this type of parameter is not contracted by the LoaderInterface
feature #1183 Remove string casts (Tobion)

This PR was submitted for the master branch but it was merged into the 2.0-experimental branch instead (closes #1183).

Discussion
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Remove string casts

| Q             | A
| ------------- | ---
| Bug fix?      | partly (consistency, performance)
| New feature?  | no
| BC breaks?    | no because interface never said something else
| Deprecations? | |no
| Tests pass?   | yes
| Fixed tickets | #1182
| License       | MIT

Should wait for symfony/symfony#8927 to be merged. Although there is no real bc break, we might want to merge this for 2.0 only.

Commits
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e5a6ec9 remove string casts from loader which was done for template reference objects, but this type of parameter is not contracted by the LoaderInterface
dadf1b3 remove unneeded string cast