[turbofan] Move graph trimming functionality to dedicated GraphTrimmer.

tools/gyp/v8.gyp

 # Copyright 2012 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 457 matching lines @@
         '../../src/compiler/frame-elider.h',
         "../../src/compiler/frame-states.cc",
         "../../src/compiler/frame-states.h",
         '../../src/compiler/gap-resolver.cc',
         '../../src/compiler/gap-resolver.h',
         '../../src/compiler/graph-builder.h',
         '../../src/compiler/graph-reducer.cc',
         '../../src/compiler/graph-reducer.h',
         '../../src/compiler/graph-replay.cc',
         '../../src/compiler/graph-replay.h',
+        '../../src/compiler/graph-trimmer.cc',
+        '../../src/compiler/graph-trimmer.h',
         '../../src/compiler/graph-visualizer.cc',
         '../../src/compiler/graph-visualizer.h',
         '../../src/compiler/graph.cc',
         '../../src/compiler/graph.h',
         '../../src/compiler/greedy-allocator.cc',
         '../../src/compiler/greedy-allocator.h',
         '../../src/compiler/instruction-codes.h',
         '../../src/compiler/instruction-selector-impl.h',
         '../../src/compiler/instruction-selector.cc',
         '../../src/compiler/instruction-selector.h',
@@ skipping 1403 matching lines @@
         }],
         ['want_separate_host_toolset==1', {
           'toolsets': ['host'],
         }, {
           'toolsets': ['target'],
         }],
       ],
     },
   ],
 }