Remove the barely used macro assemblers after merging their contents to the base

runtime/vm/flow_graph_compiler_x64.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/flow_graph_compiler.h"
 
 #include "lib/error.h"
@@ skipping 904 matching lines @@
           Immediate(FLAG_optimization_counter_threshold));
       ASSERT(function_reg == RDI);
       __ j(GREATER_EQUAL, &StubCode::OptimizeFunctionLabel());
     }
   } else {
     AddCurrentDescriptor(PcDescriptors::kEntryPatch,
                      Isolate::kNoDeoptId,
                      0);  // No token position.
   }
   __ Comment("Enter frame");
-  AssemblerMacros::EnterDartFrame(assembler(), (StackSize() * kWordSize));
+  __ EnterDartFrame((StackSize() * kWordSize));
 }
 
 
 void FlowGraphCompiler::CompileGraph() {
   InitCompiler();
   if (TryIntrinsify()) {
     // Although this intrinsified code will never be patched, it must satisfy
     // CodePatcher::CodeIsPatchable, which verifies that this code has a minimum
     // code size, and nop(2) increases the minimum code size appropriately.
     __ nop(2);
@@ skipping 759 matching lines @@
 void ParallelMoveResolver::Exchange(const Address& mem1, const Address& mem2) {
   __ Exchange(mem1, mem2);
 }
 
 
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64