Introduce WPTServe for running W3C Blink Layout tests

Tools/Scripts/webkitpy/layout_tests/servers/third_party/checkout.sh

Index: Tools/Scripts/webkitpy/layout_tests/servers/third_party/checkout.sh
diff --git a/Tools/Scripts/webkitpy/layout_tests/servers/third_party/checkout.sh b/Tools/Scripts/webkitpy/layout_tests/servers/third_party/checkout.sh
new file mode 100755
index 0000000000000000000000000000000000000000..c579e630a9fbc9fab794d050c4faaf9125b6eec3
--- /dev/null
+++ b/Tools/Scripts/webkitpy/layout_tests/servers/third_party/checkout.sh
@@ -0,0 +1,33 @@
+#!/bin/bash
+
+DIR=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )
+cd $DIR
+TARGET_DIR=$DIR/wpt
+REMOTE_REPO="https://chromium.googlesource.com/external/w3c/web-platform-tests.git"
+WPT_HEAD="aa3fb4a1d10af0bafca022b069a61c8120ceaf43"
+
+# Remove if already exists.
+[ -d "$TARGET_DIR" ] && rm -rf $TARGET_DIR
+
+# Clone the entire thingy.
+git clone $REMOTE_REPO $TARGET_DIR
+cd $TARGET_DIR && git checkout $WPT_HEAD
+
+# Grab all submodules.
+while read dir submodule commit; do
+  echo
+  echo "Working in $dir on submodule $submodule. Setting head to: $commit"
+  cd $TARGET_DIR/$dir && \
+    git submodule update --init $submodule && \
+    cd $TARGET_DIR/$dir/$submodule && \
+    git checkout $commit
+done < $DIR/WPTSubmodules
+
+# Remove all except white list.
+cd $TARGET_DIR
+rm -rf $(ls | grep -w -ve "$(cat $DIR/WPTWhiteList)")
+
+# Remove the .git dirs.
+rm -rf $TARGET_DIR/.git $TARGET_DIR/tools/.git $TARGET_DIR/tools/wptserve/.git
+
+# TODO(burnik): Handle the SSL certs.