fix Bad Smells in spoon.compiler.SpoonResourceHelper

[laughing-train]

Repairing Code Style Issues

UnnecessaryToStringCall

The toString() method is not needed in cases the underlying method handles the conversion. Also calling toString() on a String is redundant. Removing them simplifies the code.

Changes:

• Remove redudant toString() call in f.toString()

[coveralls]

Pull Request Test Coverage Report for Build #415

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• 39 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.1%) to 87.126%

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Files with Coverage Reduction	New Missed Lines	%
src/main/java/spoon/reflect/meta/impl/ModelRoleHandlers.java	12	92.61%
src/main/java/spoon/support/visitor/replace/ReplacementVisitor.java	27	96.79%

Totals
Change from base Build #408:	-0.1%
Covered Lines:	28309
Relevant Lines:	32492

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💛 - Coveralls