[interpreter, debugger] implement debugger statement.

test/cctest/interpreter/test-bytecode-generator.cc

 // Copyright 2015 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/v8.h"
 
 #include "src/compiler.h"
 #include "src/interpreter/bytecode-array-iterator.h"
 #include "src/interpreter/bytecode-generator.h"
 #include "src/interpreter/interpreter.h"
@@ skipping 7632 matching lines @@
         InstanceType::ONE_BYTE_INTERNALIZED_STRING_TYPE}},
   };
 
   for (size_t i = 0; i < arraysize(snippets); i++) {
     Handle<BytecodeArray> bytecode_array =
         helper.MakeBytecodeForFunctionBody(snippets[i].code_snippet);
     CheckBytecodeArrayEqual(snippets[i], bytecode_array);
   }
 }
 
+TEST(DoDebugger) {
+  InitializedHandleScope handle_scope;
+  BytecodeGeneratorHelper helper;
+
+  ExpectedSnippet<const char*> snippet = {"debugger;",
+                                          0,
+                                          1,
+                                          3,
+                                          {
+                                              B(Debugger),      //

[rmcilroy, 2016/02/04 12:37:17]

https://codereview.chromium.org/1665853002/ will add a B(StackCheck) at the
start of the function.

Also, could you add "// clang-format off" before and  "// clang-format on" after
the snippet, and format the snippet like the others.

[Yang, 2016/02/04 13:47:06]

Done.

+                                              B(LdaUndefined),  //
+                                              B(Return)         //
+                                          },
+                                          0};
+
+  Handle<BytecodeArray> bytecode_array =
+      helper.MakeBytecodeForFunctionBody(snippet.code_snippet);
+  CheckBytecodeArrayEqual(snippet, bytecode_array);
+}
+
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8