Revert of [debugger] remove debugger statement support from FCG/CS.

src/compiler/ast-graph-builder.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/ast-graph-builder.h"
 
 #include "src/ast/compile-time-value.h"
 #include "src/ast/scopes.h"
 #include "src/compilation-info.h"
 #include "src/compiler.h"
@@ skipping 1268 matching lines @@
 }
 
 
 void AstGraphBuilder::VisitTryFinallyStatement(TryFinallyStatement* stmt) {
   // Exception handling is supported only by going through Ignition first.
   UNREACHABLE();
 }
 
 
 void AstGraphBuilder::VisitDebuggerStatement(DebuggerStatement* stmt) {
-  // Debugger statement is supported only by going through Ignition first.
-  UNREACHABLE();
+  Node* node = NewNode(javascript()->Debugger());
+  PrepareFrameState(node, stmt->DebugBreakId());
+  environment()->MarkAllLocalsLive();
 }
 
 
 void AstGraphBuilder::VisitFunctionLiteral(FunctionLiteral* expr) {
   // Find or build a shared function info.
   Handle<SharedFunctionInfo> shared_info =
       Compiler::GetSharedFunctionInfo(expr, info()->script(), info());
   CHECK(!shared_info.is_null());  // TODO(mstarzinger): Set stack overflow?
 
   // Create node to instantiate a new closure.
@@ skipping 2008 matching lines @@
     float invocation_frequency, LoopAssignmentAnalysis* loop_assignment,
     SourcePositionTable* source_positions, int inlining_id)
     : AstGraphBuilder(local_zone, info, jsgraph, invocation_frequency,
                       loop_assignment),
       source_positions_(source_positions),
       start_position_(info->shared_info()->start_position(), inlining_id) {}
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8