Introduce Diamond, a helper for building diamond-shaped control patterns.

test/unittests/compiler/node-test-utils.h

Index: test/unittests/compiler/node-test-utils.h
diff --git a/test/unittests/compiler/node-test-utils.h b/test/unittests/compiler/node-test-utils.h
index 308da4cfd31dd61a049e021a37787d6a05fd8f1c..89fcc4b87cfb7463c378ec28711e316853b8f8a8 100644
--- a/test/unittests/compiler/node-test-utils.h
+++ b/test/unittests/compiler/node-test-utils.h
@@ -56,6 +56,9 @@ Matcher<Node*> IsPhi(const Matcher<MachineType>& type_matcher,
                      const Matcher<Node*>& value0_matcher,
                      const Matcher<Node*>& value1_matcher,
                      const Matcher<Node*>& merge_matcher);
+Matcher<Node*> IsEffectPhi(const Matcher<Node*>& effect0_matcher,
+                           const Matcher<Node*>& effect1_matcher,
+                           const Matcher<Node*>& merge_matcher);
 Matcher<Node*> IsProjection(const Matcher<size_t>& index_matcher,
                             const Matcher<Node*>& base_matcher);
 Matcher<Node*> IsCall(const Matcher<CallDescriptor*>& descriptor_matcher,