[inspector] Increased chances of successful InjectedScriptSource compilation

test/inspector/inspector.isolate

 # 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.
 {
   'conditions': [
     ['v8_enable_inspector==1', {
       'variables': {
         'files': [
           './console/',
           './cpu-profiler/',
           './debugger/',
           './inspector.status',
           './json-parse-expected.txt',
           './json-parse.js',
           './protocol-test.js',
           './runtime/',
           './testcfg.py',
+          '../../src/inspector/injected-script-source.js',
           '<(PRODUCT_DIR)/inspector-test<(EXECUTABLE_SUFFIX)',
         ],
       },
     }],
   ],
   'includes': [
     '../../src/base.isolate',
     '../../tools/testrunner/testrunner.isolate',
   ],
 }