Make String16 consturctors non-inline to save binary size (150kb)

src/inspector/string-16.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_STRING16_H_
 #define V8_INSPECTOR_STRING16_H_
 
 #include <stdint.h>
 #include <cctype>
 #include <climits>
 #include <cstring>
 #include <string>
 #include <vector>
 
 namespace v8_inspector {
 
 using UChar = uint16_t;
 
 class String16 {
  public:
   static const size_t kNotFound = static_cast<size_t>(-1);
 
-  String16() {}
-  String16(const String16& other)
-      : m_impl(other.m_impl), hash_code(other.hash_code) {}
-  String16(String16&& other)
-      : m_impl(std::move(other.m_impl)), hash_code(other.hash_code) {}
-  String16(const UChar* characters, size_t size) : m_impl(characters, size) {}
-  String16(const UChar* characters)  // NOLINT(runtime/explicit)
-      : m_impl(characters) {}
-  String16(const char* characters)  // NOLINT(runtime/explicit)
-      : String16(characters, std::strlen(characters)) {}
-  String16(const char* characters, size_t size) {
-    m_impl.resize(size);
-    for (size_t i = 0; i < size; ++i) m_impl[i] = characters[i];
-  }
-  explicit String16(const std::basic_string<UChar>& impl) : m_impl(impl) {}
+  String16();
+  String16(const String16& other);
+  String16(String16&& other);
+  String16(const UChar* characters, size_t size);
+  String16(const UChar* characters);  // NOLINT(runtime/explicit)
+  String16(const char* characters);   // NOLINT(runtime/explicit)
+  String16(const char* characters, size_t size);
+  explicit String16(const std::basic_string<UChar>& impl);
 
-  String16& operator=(const String16& other) {
-    m_impl = other.m_impl;
-    hash_code = other.hash_code;
-    return *this;
-  }
-  String16& operator=(String16&& other) {
-    m_impl = std::move(other.m_impl);
-    hash_code = other.hash_code;
-    return *this;
-  }
+  String16& operator=(const String16& other);
+  String16& operator=(String16&& other);
 
   static String16 fromInteger(int);
   static String16 fromInteger(size_t);
   static String16 fromDouble(double);
   static String16 fromDouble(double, int precision);
 
   int toInteger(bool* ok = nullptr) const;
   String16 stripWhiteSpace() const;
   const UChar* characters16() const { return m_impl.c_str(); }
   size_t length() const { return m_impl.length(); }
@@ skipping 98 matching lines @@
   std::size_t operator()(const v8_inspector::String16& string) const {
     return string.hash();
   }
 };
 
 }  // namespace std
 
 #endif  // !defined(__APPLE__) || defined(_LIBCPP_VERSION)
 
 #endif  // V8_INSPECTOR_STRING16_H_