Fix WinHttpHandler outerloop tests for deflate

[stephentoub]

Fixes #43293
Fixes #43292

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[ManickaP]

/azp run runtime-libraries-coreclr outerloop

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[geoffkizer]

WinHttpHandler targets netstandard2.0 and still erroneously uses DeflateStream rather than ZlibStream for deflate.

This is in our code in WinHttpHandler, right? Not in winhttp proper?

[stephentoub]

This is in our code in WinHttpHandler, right? Not in winhttp proper?

Correct.

runtime/src/libraries/System.Net.Http.WinHttpHandler/src/System/Net/Http/WinHttpResponseParser.cs

Lines 83 to 88 in 98eee05

	else if ((manuallyProcessedDecompressionMethods & DecompressionMethods.Deflate) == DecompressionMethods.Deflate &&
	CharArrayHelpers.EqualsOrdinalAsciiIgnoreCase(EncodingNameDeflate, buffer, contentEncodingStartIndex, contentEncodingLength))
	{
	decompressedStream = new DeflateStream(responseStream, CompressionMode.Decompress);
	stripEncodingHeaders = true;
	}

This didn't seem like a good enough reason to start shipping a new asset.

[stephentoub]

This didn't seem like a good enough reason to start shipping a new asset.

Though, we could use reflection...