diff -u -r webkitgtk-2.16.5/Source/cmake/OptionsCommon.cmake webkitgtk-2.16.5-gcc7/Source/cmake/OptionsCommon.cmake
--- webkitgtk-2.16.5/Source/cmake/OptionsCommon.cmake	2017-05-06 10:48:27.000000000 +0200
+++ webkitgtk-2.16.5-gcc7/Source/cmake/OptionsCommon.cmake	2017-06-27 13:15:26.858090686 +0200
@@ -38,7 +38,9 @@
 define_property(TARGET PROPERTY FOLDER INHERITED BRIEF_DOCS "folder" FULL_DOCS "IDE folder name")
 
 if (COMPILER_IS_GCC_OR_CLANG)
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-expansion-to-defined -Wno-implicit-fallthrough")
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fno-exceptions -fno-strict-aliasing")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-expansion-to-defined -Wno-implicit-fallthrough")
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-exceptions -fno-strict-aliasing -fno-rtti")
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++1y")
 endif ()
diff -u -r webkitgtk-2.16.5/Source/WTF/wtf/text/StringImpl.h webkitgtk-2.16.5-gcc7/Source/WTF/wtf/text/StringImpl.h
--- webkitgtk-2.16.5/Source/WTF/wtf/text/StringImpl.h	2017-02-20 17:20:15.000000000 +0100
+++ webkitgtk-2.16.5-gcc7/Source/WTF/wtf/text/StringImpl.h	2017-06-27 13:13:57.801527350 +0200
@@ -581,29 +581,7 @@
     // FIXME: Does this really belong in StringImpl?
     template <typename T> static void copyChars(T* destination, const T* source, unsigned numCharacters)
     {
-        if (numCharacters == 1) {
-            *destination = *source;
-            return;
-        }
-
-        if (numCharacters <= s_copyCharsInlineCutOff) {
-            unsigned i = 0;
-#if (CPU(X86) || CPU(X86_64))
-            const unsigned charsPerInt = sizeof(uint32_t) / sizeof(T);
-
-            if (numCharacters > charsPerInt) {
-                unsigned stopCount = numCharacters & ~(charsPerInt - 1);
-
-                const uint32_t* srcCharacters = reinterpret_cast<const uint32_t*>(source);
-                uint32_t* destCharacters = reinterpret_cast<uint32_t*>(destination);
-                for (unsigned j = 0; i < stopCount; i += charsPerInt, ++j)
-                    destCharacters[j] = srcCharacters[j];
-            }
-#endif
-            for (; i < numCharacters; ++i)
-                destination[i] = source[i];
-        } else
-            memcpy(destination, source, numCharacters * sizeof(T));
+        memcpy(destination, source, numCharacters * sizeof(T));
     }
 
     ALWAYS_INLINE static void copyChars(UChar* destination, const LChar* source, unsigned numCharacters)