Remove C# dynamic support from JsonNode

[steveharter]

See discussion at #53195

We can always add it back in v.next, or add a "new (more modern) dynamic" if\when that comes out.

[ghost]

Tagging subscribers to this area: @eiriktsarpalis, @layomia
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Issue Details

---

See discussion at #53195

We can always add it back in v.next, or add a "new (more modern) dynamic" if\when that comes out.

Author:	steveharter
Assignees:	steveharter
Labels:	area-System.Text.Json
Milestone:	-

[ghost]

Note regarding the new-api-needs-documentation label:

This serves as a reminder for when your PR is modifying a ref *.cs file and adding/modifying public APIs, to please make sure the API implementation in the src *.cs file is documented with triple slash comments, so the PR reviewers can sign off that change.

[layomia]

I'm not sure we should take this approach. In the PR to support all the collection types in source-gen mode, #55566, these converters are being used by the source generator. That PR modifies them such that they perform no reflection/rooting (in source-gen mode), e.g. this diff.

I believe the plan is to replace the trimming tests that use the pre-existing serializer overloads with new ones that use the source generator instead - #53437. Given this, could we disable the failing Stack test in this PR and replace it after #55566 goes in? cc @eerhardt

[eerhardt]

Agreed. I'd rather we just delete the trimming test until we have source gen support.

Do we know why this change is causing the test to fail though?

[steveharter]

Test failure appears infrastructure-related:

2021-07-12 21:45:20,080: INFO: 4546600384: run(141): main: Main thread starting 10 workers
2021-07-12 21:45:25,241: WARNING: 4546600384: run(169): main: Unhandled exception trying to report to ADO: no element found: line 33, column 3
2021-07-12 21:45:25,263: WARNING: 4546600384: run(170): main: We'll attempt to count the XUnit results and if XML is present and no failures, return 0
Searching '/tmp/helix/working/A2B508F9/w/B04809E0/e/..' for log files
Found log '/tmp/helix/working/A2B508F9/w/B04809E0/e/../console.b67234d6.log'
Uri 'https://helixre8s23ayyeko0k025g8.blob.core.windows.net/dotnet-runtime-refs-pull-55430-merge-18140ce380bd48d098/System.Runtime.InteropServices.Tests/console.b67234d6.log?sv=2019-07-07&se=2021-08-02T01%3A18%3A16Z&sr=c&sp=rl&sig=AEuDxHzBeH%2Bdg1mQ0137%2FiE1DPsgVpAbFF7TM3JZl40%3D'
Generated log list: console.b67234d6.log:
https://helixre8s23ayyeko0k025g8.blob.core.windows.net/dotnet-runtime-refs-pull-55430-merge-18140ce380bd48d098/System.Runtime.InteropServices.Tests/console.b67234d6.log?sv=2019-07-07&se=2021-08-02T01%3A18%3A16Z&sr=c&sp=rl&sig=AEuDxHzBeH%2Bdg1mQ0137%2FiE1DPsgVpAbFF7TM3JZl40%3D
Searching '/private/tmp/helix/working/A2B508F9/w/B04809E0/e' for test results files
Found results file /private/tmp/helix/working/A2B508F9/w/B04809E0/e/testResults.xml with format xunit
Reporting has failed. Running mitigation for https://github.com/dotnet/arcade/issues/7371
Searching '/private/tmp/helix/working/A2B508F9/w/B04809E0/e' for test results files
Found results file /private/tmp/helix/working/A2B508F9/w/B04809E0/e/testResults.xml Searching '/tmp/helix/working/A2B508F9/w/B04809E0/uploads' for test results files
Reporter script has failed, but XUnit test results show no failures.

[steveharter]

Test failures unrelated:

System.Net.Http.WinHttpHandler.Functional.Tests Test System.Net.Quic.Tests.MsQuicTests.ByteMixingOrNativeAVE_MinimalFailingTest has failed
System.Net.Requests.Tests

[ghost]

Tagging @dotnet/compat for awareness of the breaking change.

[ericstj]

Marking this as breaking since it's a break from previous preview (which is acceptable, but should be messaged). Please fill out the template here: https://github.com/dotnet/docs/issues/new?assignees=&labels=&template=dotnet-breaking-change.md&title=

[steveharter]

Breaking change issue: dotnet/docs#25105