Create a minimal webkit_common static library for use in browser process

public/common/WebAssertion.h

Index: public/common/WebAssertion.h
diff --git a/public/common/WebAssertion.h b/public/common/WebAssertion.h
new file mode 100644
index 0000000000000000000000000000000000000000..470da7a12558ca89c434f3dd98a0985797081284
--- /dev/null
+++ b/public/common/WebAssertion.h
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+#ifndef WebAssertion_h
+#define WebAssertion_h
+
+#include "WebCommonExport.h"
+
+namespace WebKit {
+
+BLINK_COMMON_EXPORT void failedAssertion(const char* file, int line, const char* function, const char* assertion);
+
+} // namespace WebKit
+
+// Ideally, only use inside the public directory but outside of WEBKIT_IMPLEMENTATION blocks.  (Otherwise use WTF's ASSERT.)
+#if defined(NDEBUG)
+#define WEBKIT_ASSERT(assertion) ((void)0)
+#else
+#define WEBKIT_ASSERT(assertion) do { \
+    if (!(assertion)) \
+        failedAssertion(__FILE__, __LINE__, __FUNCTION__, #assertion); \
+} while (0)
+#endif
+
+#define WEBKIT_ASSERT_NOT_REACHED() WEBKIT_ASSERT(0)
+
+#endif // WebAssertion_h