[code-reflection] RFR: Null check only when selector expression of switch expression is of reference type [v2]

[Mourad Abbay]

> Generate lowered form of switch expression that check if the selector expression is null only when the selector expression has type reference.

Mourad Abbay has updated the pull request incrementally with two additional commits since the last revision:

 - Test lowering switch that has a selector expression of type primitive.
 - Change the way we check if selector expression is of type primitive.

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Changes:
  - all: https://git.openjdk.org/babylon/pull/112/files
  - new: https://git.openjdk.org/babylon/pull/112/files/c1b918ac..b01ba094

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=babylon&pr=112&range=01
 - incr: https://webrevs.openjdk.org/?repo=babylon&pr=112&range=00-01

  Stats: 23 lines in 2 files changed: 18 ins; 4 del; 1 mod
  Patch: https://git.openjdk.org/babylon/pull/112.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/112/head:pull/112

PR: https://git.openjdk.org/babylon/pull/112