Added errno (or GetLastError code) to crash dump when systemAllocPages fails.

third_party/WebKit/Source/wtf/PageAllocator.h

Index: third_party/WebKit/Source/wtf/PageAllocator.h
diff --git a/third_party/WebKit/Source/wtf/PageAllocator.h b/third_party/WebKit/Source/wtf/PageAllocator.h
index 5714f1692020b607e9fbf562bbbf1ef046f772b1..59bc7ea8673e3b6d3d6e6e9f38905c36e033b2b8 100644
--- a/third_party/WebKit/Source/wtf/PageAllocator.h
+++ b/third_party/WebKit/Source/wtf/PageAllocator.h
@@ -136,6 +136,12 @@ WTF_EXPORT ALWAYS_INLINE uintptr_t roundDownToSystemPage(uintptr_t address)
     return address & kSystemPageBaseMask;
 }
 
+// Only allowed inside WTF for investigating WTF::initializeWithoutV8 crashes.
+// Guess, the function fails because of mmap (or VirtualAlloc) failure.
+// The following function returns errno (or GetLastError code) when mmap
+// (or VirtualAlloc) fails.
+uint32_t getAllocPageErrorCode();
+
 } // namespace WTF
 
 #endif // WTF_PageAllocator_h