Revert of Build the Clang plugin on Windows.

tools/clang/plugins/CMakeLists.txt

-set(plugin_sources
-  ChromeClassTester.cpp
-  FindBadConstructsAction.cpp
-  FindBadConstructsConsumer.cpp)
+add_llvm_loadable_module(libFindBadConstructs
+                         ChromeClassTester.cpp
+                         FindBadConstructsAction.cpp
+                         FindBadConstructsConsumer.cpp
+                        )
 
-if(WIN32)
-  # Clang doesn't support loadable modules on Windows. Unfortunately, building
-  # the plugin as a static library and linking clang against it doesn't work.
-  # Since clang doesn't reference any symbols in our static library, the linker
-  # strips it out completely.
-  # Instead, we rely on the fact that the SOURCES property of a target is no
-  # read-only after CMake 3.1 and use it to compile the plugin directly into
-  # clang...
-  cmake_minimum_required(VERSION 3.1)
-  # Paths must be absolute, since we're modifying a target in another directory.
-  set(absolute_sources "")
-  foreach(source ${plugin_sources})
-    list(APPEND absolute_sources ${CMAKE_CURRENT_SOURCE_DIR}/${source})
-  endforeach()
-  set_property(TARGET clang APPEND PROPERTY SOURCES ${absolute_sources})
-else()
-  add_llvm_loadable_module(libFindBadConstructs ${plugin_sources})
-  add_dependencies(libFindBadConstructs clang)
+add_dependencies(libFindBadConstructs clang)
 
-  cr_install(TARGETS libFindBadConstructs LIBRARY DESTINATION lib)
+cr_install(TARGETS libFindBadConstructs LIBRARY DESTINATION lib)
 
-  # TODO(dcheng): Rewrite the test framework so it works on Windows too.
-  cr_add_test(plugins_test
-    ${CMAKE_CURRENT_SOURCE_DIR}/tests/test.sh
-    ${CMAKE_BINARY_DIR}/bin/clang
-    $<TARGET_FILE:libFindBadConstructs>
-    )
-endif()
+cr_add_test(plugins_test
+  ${CMAKE_CURRENT_SOURCE_DIR}/tests/test.sh
+  ${CMAKE_BINARY_DIR}/bin/clang
+  $<TARGET_FILE:libFindBadConstructs>
+  )