[GR-7501] Various smaller fixes.

...e/truffle/r/library/fastrShiny/shiny/R/fastr-imageutils.R

.../truffle/r/library/fastrShiny/shiny/R/fastr-render-plot.R

...n/src/com/oracle/truffle/r/nodes/builtin/base/Repeat.java

...racle/truffle/r/nodes/access/vector/PositionCastNode.java

.../src/com/oracle/truffle/r/nodes/unary/CastSymbolNode.java

...rc/com/oracle/truffle/r/runtime/ops/BinaryArithmetic.java

...est/src/com/oracle/truffle/r/test/ExpectedTestOutput.test

.../oracle/truffle/r/test/builtins/TestBuiltin_asvector.java

...c/com/oracle/truffle/r/test/builtins/TestBuiltin_rep.java

...cle/truffle/r/test/library/base/TestSimpleArithmetic.java