Revert "reflect: handle zero-sized fields of directly-stored structures correctly"

This reverts commit b338856 (CL 694195)

Reason for revert: still causing compiler failures on Google test code

Change-Id: I2a9b0f9a57fe2b6977238bbfbefb572545210b9f
Reviewed-on: https://go-review.googlesource.com/c/go/+/694995
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Keith Randall <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>

Author: randall77

src/reflect/value.go

@@ -1277,17 +1277,6 @@ func (v Value) Field(i int) Value {
 			fl |= flagStickyRO
 		}
 	}
-	if fl&flagIndir == 0 && typ.Size() == 0 {
-		// Special case for picking a field out of a direct struct.
-		// A direct struct must have a pointer field and possibly a
-		// bunch of zero-sized fields. We must return the zero-sized
-		// fields indirectly, as only ptr-shaped things can be direct.
-		// See issue 74935.
-		// We use nil instead of v.ptr as it doesn't matter and
-		// we can avoid pinning a possibly now-unused object.
-		return Value{typ, nil, fl | flagIndir}
-	}
-
 	// Either flagIndir is set and v.ptr points at struct,
 	// or flagIndir is not set and v.ptr is the actual struct data.
 	// In the former case, we want v.ptr + offset.