[test] Sync unittests gn build

Fix after:
https://codereview.chromium.org/2060743002/
https://codereview.chromium.org/2086653003/

BUG=v8:5086, v8:5092, v8:4124
TBR=bmeurer@chromium.org, yangguo@chromium.org,  bbudge@chromium.org

NOTRY=true

Review-Url: https://codereview.chromium.org/2095313002
Cr-Commit-Position: refs/heads/master@{#37274}

test/unittests/BUILD.gn

@@ -16,6 +16,7 @@ v8_executable("unittests") {
     "base/division-by-constant-unittest.cc",
     "base/flags-unittest.cc",
     "base/functional-unittest.cc",
+    "base/ieee754-unittest.cc",
     "base/iterator-unittest.cc",
     "base/logging-unittest.cc",
     "base/platform/condition-variable-unittest.cc",
@@ -104,6 +105,7 @@ v8_executable("unittests") {
     "libplatform/task-queue-unittest.cc",
     "libplatform/worker-thread-unittest.cc",
     "locked-queue-unittest.cc",
+    "register-configuration-unittest.cc",
     "run-all-unittests.cc",
     "test-utils.cc",
     "test-utils.h",