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

src/full-codegen/full-codegen.cc

Index: src/full-codegen/full-codegen.cc
diff --git a/src/full-codegen/full-codegen.cc b/src/full-codegen/full-codegen.cc
index 8de7eeb02e8ce1fbcd8ea143d752adefe713f3ff..54a862475f0ac27a1551d3c5ef9b9fc06151e863 100644
--- a/src/full-codegen/full-codegen.cc
+++ b/src/full-codegen/full-codegen.cc
@@ -1228,8 +1228,13 @@
 
 
 void FullCodeGenerator::VisitDebuggerStatement(DebuggerStatement* stmt) {
-  // Debugger statement is not supported.
-  UNREACHABLE();
+  Comment cmnt(masm_, "[ DebuggerStatement");
+  SetStatementPosition(stmt);
+
+  __ DebugBreak();
+  __ MaybeDropFrames();
+
+  PrepareForBailoutForId(stmt->DebugBreakId(), BailoutState::NO_REGISTERS);
 }