[inspector] Use relative path to the third_party

src/inspector/inspector.gyp

 # Copyright 2016 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.
 
 {
   'variables': {
-    'protocol_path': '<(PRODUCT_DIR)/../../third_party/inspector_protocol',
+    'protocol_path': '../../third_party/inspector_protocol',
   },
   'includes': [
     'inspector.gypi',
     '<(PRODUCT_DIR)/../../../third_party/inspector_protocol/inspector_protocol.gypi',
   ],
   'targets': [
     { 'target_name': 'inspector_injected_script',
       'type': 'none',
       'actions': [
         {
@@ skipping 72 matching lines @@
             'js_protocol.json',
             'inspector_protocol_config.json',
             '<@(inspector_protocol_files)',
           ],
           'outputs': [
             '<@(inspector_generated_sources)',
           ],
           'action': [
             'python',
             '<(protocol_path)/CodeGenerator.py',
-            '--jinja_dir', '<(PRODUCT_DIR)/../../third_party',
+            '--jinja_dir', '../../third_party',
             '--output_base', '<(SHARED_INTERMEDIATE_DIR)/src/inspector',
             '--config', 'inspector_protocol_config.json',
           ],
           'message': 'Generating inspector protocol sources from protocol json',
         },
       ]
     },
   ],
 }