It looks like webkit gtk port is not compatible for cygwin build following error occurs Unable to find definition for dictionary named 'EventInit'! at Source/WebCore/bindings/scripts/CodeGeneratorJS.pm line 120. $VAR1 = ' at Source/WebCore/bindings/scripts/CodeGeneratorJS.pm line 2763. CodeGeneratorJS::GenerateDictionaryImplementationContent(IDLDictionary=HASH(0xa00a11120), "WebKitPlaybackTargetAvailabilityEvent::Init", IDLInterface=HASH(0xa00a09a60)) called at Source/WebCore/bindings/scripts/CodeGeneratorJS.pm line 2940 CodeGeneratorJS::GenerateDictionariesImplementationContent(IDLInterface=HASH(0xa00a09a60), ARRAY(0xa00a11258)) called at Source/WebCore/bindings/scripts/CodeGeneratorJS.pm line 4454 CodeGeneratorJS::GenerateImplementation(CodeGeneratorJS=HASH(0xa009f2020), IDLInterface=HASH(0xa00a09a60), ARRAY(0xa00a112b8), ARRAY(0xa00a11258)) called at Source/WebCore/bindings/scripts/CodeGeneratorJS.pm line 179 CodeGeneratorJS::GenerateInterface(CodeGeneratorJS=HASH(0xa009f2020), IDLInterface=HASH(0xa00a09a60), "LANGUAGE_JAVASCRIPT ENABLE_3D_TRANSFORMS ENABLE_CONTEXT_MENU"..., ARRAY(0xa00a112b8), ARRAY(0xa00a11258)) called at Source/WebCore/bindings/scripts/CodeGenerator.pm line 258 CodeGenerator::ProcessInterfaces(CodeGenerator=HASH(0xa00a11180), IDLDocument=HASH(0xa00a11168), "LANGUAGE_JAVASCRIPT ENABLE_3D_TRANSFORMS ENABLE_CONTEXT_MENU"..., CodeGeneratorJS=HASH(0xa009f2020)) called at Source/WebCore/bindings/scripts/CodeGenerator.pm line 179 CodeGenerator::ProcessDocument(CodeGenerator=HASH(0xa00a11180), IDLDocument=HASH(0xa00a11168), "LANGUAGE_JAVASCRIPT ENABLE_3D_TRANSFORMS ENABLE_CONTEXT_MENU"...) called at Source/WebCore/bindings/scripts/generate-bindings.pl line 133 main::generateBindings(undef) called at Source/WebCore/bindings/scripts/generate-bindings.pl line 83