[inspector] fix timestamp formatting with non C locales

src/inspector/string-util.h

 // 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.
 
 #ifndef V8_INSPECTOR_STRINGUTIL_H_
 #define V8_INSPECTOR_STRINGUTIL_H_
 
 #include "src/base/macros.h"
 #include "src/inspector/string-16.h"
 
@@ skipping 10 matching lines @@
 
 class StringUtil {
  public:
   static String substring(const String& s, size_t pos, size_t len) {
     return s.substring(pos, len);
   }
   static String fromInteger(int number) { return String::fromInteger(number); }
   static String fromInteger(size_t number) {
     return String::fromInteger(number);
   }
-  static String fromDouble(double number) { return String::fromDouble(number); }
+  static String fromDouble(double number) {
+    return String::fromDoubleForcePointAsSeparator(number);
+  }
   static const size_t kNotFound = String::kNotFound;
   static void builderReserve(StringBuilder& builder, size_t capacity) {
     builder.reserveCapacity(capacity);
   }
 };
 
 std::unique_ptr<protocol::Value> parseJSON(const StringView& json);
 std::unique_ptr<protocol::Value> parseJSON(const String16& json);
 
 }  // namespace protocol
@@ skipping 24 matching lines @@
   explicit StringBufferImpl(String16&);
   String16 m_owner;
   StringView m_string;
 
   DISALLOW_COPY_AND_ASSIGN(StringBufferImpl);
 };
 
 }  //  namespace v8_inspector
 
 #endif  // V8_INSPECTOR_STRINGUTIL_H_