[turbofan] First step of Operator refactoring.

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index d2feecb8aff83621e5314a344da1ccbbe1d89fc9..57a2542a36d6cea1e0585cf339a0e8c7a1ef4cbc 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -460,6 +460,7 @@ source_set("v8_base") {
     "src/codegen.h",
     "src/compilation-cache.cc",
     "src/compilation-cache.h",
+    "src/compiler/access-builder.cc",
     "src/compiler/access-builder.h",
     "src/compiler/ast-graph-builder.cc",
     "src/compiler/ast-graph-builder.h",
@@ -529,6 +530,7 @@ source_set("v8_base") {
     "src/compiler/opcodes.h",
     "src/compiler/operator-properties-inl.h",
     "src/compiler/operator-properties.h",
+    "src/compiler/operator.cc",
     "src/compiler/operator.h",
     "src/compiler/phi-reducer.h",
     "src/compiler/pipeline.cc",
@@ -547,6 +549,7 @@ source_set("v8_base") {
     "src/compiler/simplified-node-factory.h",
     "src/compiler/simplified-operator-reducer.cc",
     "src/compiler/simplified-operator-reducer.h",
+    "src/compiler/simplified-operator.cc",
     "src/compiler/simplified-operator.h",
     "src/compiler/source-position.cc",
     "src/compiler/source-position.h",