cmake: don't download WebKit unless we're gonna need it

cmake/scripts/DownloadWebKit.cmake

@@ -0,0 +1,9 @@
+file(DOWNLOAD ${WEBKIT_DOWNLOAD_URL} ${CACHE_PATH}/${WEBKIT_FILENAME} SHOW_PROGRESS)
+file(ARCHIVE_EXTRACT INPUT ${CACHE_PATH}/${WEBKIT_FILENAME} DESTINATION ${CACHE_PATH} TOUCH)
+file(REMOVE ${CACHE_PATH}/${WEBKIT_FILENAME})
+file(REMOVE_RECURSE ${WEBKIT_PATH})
+file(RENAME ${CACHE_PATH}/bun-webkit ${WEBKIT_PATH})
+
+if(APPLE)
+  file(REMOVE_RECURSE ${WEBKIT_PATH}/include/unicode)
+endif()

cmake/targets/BuildBun.cmake

@@ -1060,6 +1060,7 @@ foreach(dependency ${BUN_DEPENDENCIES})
 endforeach()
 
 list(TRANSFORM BUN_DEPENDENCIES TOLOWER OUTPUT_VARIABLE BUN_TARGETS)
+list(APPEND BUN_DEPENDENCIES WebKit)
 add_custom_target(dependencies DEPENDS ${BUN_TARGETS})
 
 if(APPLE)

cmake/tools/SetupWebKit.cmake

@@ -87,12 +87,23 @@ set(WEBKIT_NAME bun-webkit-${WEBKIT_OS}-${WEBKIT_ARCH}${WEBKIT_SUFFIX})
 set(WEBKIT_FILENAME ${WEBKIT_NAME}.tar.gz)
 setx(WEBKIT_DOWNLOAD_URL https://github.com/oven-sh/WebKit/releases/download/autobuild-${WEBKIT_VERSION}/${WEBKIT_FILENAME})
 
-file(DOWNLOAD ${WEBKIT_DOWNLOAD_URL} ${CACHE_PATH}/${WEBKIT_FILENAME} SHOW_PROGRESS)
-file(ARCHIVE_EXTRACT INPUT ${CACHE_PATH}/${WEBKIT_FILENAME} DESTINATION ${CACHE_PATH} TOUCH)
-file(REMOVE ${CACHE_PATH}/${WEBKIT_FILENAME})
-file(REMOVE_RECURSE ${WEBKIT_PATH})
-file(RENAME ${CACHE_PATH}/bun-webkit ${WEBKIT_PATH})
-
-if(APPLE)
-  file(REMOVE_RECURSE ${WEBKIT_INCLUDE_PATH}/unicode)
-endif()
+register_command(
+  TARGET
+    WebKit
+  COMMENT
+    "Downloading WebKit"
+  COMMAND
+    ${CMAKE_COMMAND}
+      -DCACHE_PATH=${CACHE_PATH}
+      -DWEBKIT_DOWNLOAD_URL=${WEBKIT_DOWNLOAD_URL}
+      -DWEBKIT_FILENAME=${WEBKIT_FILENAME}
+      -DWEBKIT_PATH=${WEBKIT_PATH}
+      -P ${CWD}/cmake/scripts/DownloadWebKit.cmake
+  SOURCES
+    ${CWD}/cmake/scripts/DownloadWebKit.cmake
+  OUTPUTS
+    ${WEBKIT_LIB_PATH}/libWTF.a
+    ${WEBKIT_LIB_PATH}/libJavaScriptCore.a
+    ${WEBKIT_LIB_PATH}/libbmalloc.a
+  ALWAYS_RUN
+)