[GR-2798] Fixed various R debugger problems.

...rc/com/oracle/truffle/r/engine/RRuntimeASTAccessImpl.java

...oracle/truffle/r/nodes/builtin/helpers/DebugHandling.java

...nodes/src/com/oracle/truffle/r/nodes/control/ForNode.java

...e.r.runtime/src/com/oracle/truffle/r/runtime/RSource.java

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

...ruffle.r.test/src/com/oracle/truffle/r/test/TestBase.java

.../src/com/oracle/truffle/r/test/generate/FastRSession.java

...le/truffle/r/test/library/utils/TestInteractiveDebug.java