RFR: [type-classes] Fix issue with type class op resolution inside speculative attribution [v2]

[Maurizio Cimadamore]

> During speculative attribution of lambda expressions, we might get to the unary/binary op resolution code with erroneous types.
> When this happens, type class witness resolution fails if Numerical/Integral are tweaked to contain witness methods.
> 
> This PR fixes this condition and adds a test.

Maurizio Cimadamore has updated the pull request incrementally with one additional commit since the last revision:

  Address review comments
  Beef up test to check various erroneous arguments permutations

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Changes:
  - all: https://git.openjdk.org/valhalla/pull/1981/files
  - new: https://git.openjdk.org/valhalla/pull/1981/files/a14b824d..31888324

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=valhalla&pr=1981&range=01
 - incr: https://webrevs.openjdk.org/?repo=valhalla&pr=1981&range=00-01

  Stats: 7 lines in 2 files changed: 2 ins; 3 del; 2 mod
  Patch: https://git.openjdk.org/valhalla/pull/1981.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1981/head:pull/1981

PR: https://git.openjdk.org/valhalla/pull/1981