Migration: standardize method names in EdgeBuilderTest.
Migration: standardize method names in EdgeBuilderTest.

Two methods had names beginning with "visit", to reflect the name of
the visitor method they tested.  But this was inconsistent with the
rest of the methods in EdgeBuilderTest, which are simply named after
the structure whose visitor method they test.

Change-Id: I4616eeff959f4ef84fc8a5da3263ab9c88d8fba2
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/107742
Reviewed-by: Brian Wilkerson <1f7641b6b14c52b9163524ab8d9aabff80176f21@google.com>

dart-archive/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-archive/dart-sdk