Implement File constructor.

LayoutTests/http/tests/xmlhttprequest/post-formdata-expected.txt

Index: LayoutTests/http/tests/xmlhttprequest/post-formdata-expected.txt
diff --git a/LayoutTests/http/tests/xmlhttprequest/post-formdata-expected.txt b/LayoutTests/http/tests/xmlhttprequest/post-formdata-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..5d1e5a7afe6ac28a34486cdcb4a7080e54c46202
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+++ b/LayoutTests/http/tests/xmlhttprequest/post-formdata-expected.txt
@@ -0,0 +1,16 @@
+Test verifies that FormData is sent correctly when using XMLHttpRequest asynchronously.
+
+On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
+
+
+PASS echoResult is "string=string value"
+PASS echoResult is "bareBlob=blob:application/octet-stream:blob-value"
+PASS echoResult is "mimeBlob=blob:text/html:blob-value"
+PASS echoResult is "namedBlob=blob-file.txt:application/octet-stream:blob-value"
+PASS echoResult is "bareFile=file-name.txt:application/octet-stream:file-value"
+PASS echoResult is "mimeFile=file-name.html:text/html:file-value"
+FAIL echoResult should be bareFile=file-name-override.html:text/html:file-value. Was renamedFile=file-name-override.html:text/html:file-value.
+PASS successfullyParsed is true
+
+TEST COMPLETE
+