[code-reflection] RFR: Update ReflectMethods.BodyScanner.coerce to handle null targetType [v2]

[Mourad Abbay]

> `ReflectMethods.BodyScanner.coerce` wasn't handling `null` targetType. For example, a `null` targetType may propagate to reach the method `coerce` when visiting case body of switch statement.

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

 - Move the checks out of coerce
 - Set bodyType to void when scanning a switch expression

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Changes:
  - all: https://git.openjdk.org/babylon/pull/536/files
  - new: https://git.openjdk.org/babylon/pull/536/files/3a58bffc..3b7ad47a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=babylon&pr=536&range=01
 - incr: https://webrevs.openjdk.org/?repo=babylon&pr=536&range=00-01

  Stats: 8 lines in 1 file changed: 0 ins; 6 del; 2 mod
  Patch: https://git.openjdk.org/babylon/pull/536.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/536/head:pull/536

PR: https://git.openjdk.org/babylon/pull/536