Add SourceFileEdit.time field.

pkg/analysis_server/tool/spec/spec_input.html

Index: pkg/analysis_server/tool/spec/spec_input.html
diff --git a/pkg/analysis_server/tool/spec/spec_input.html b/pkg/analysis_server/tool/spec/spec_input.html
index dccffeb366ea62a7a24bab1907f68c146036535d..55553bb8a68c37845bd9ae84743165a2aedd8fa7 100644
--- a/pkg/analysis_server/tool/spec/spec_input.html
+++ b/pkg/analysis_server/tool/spec/spec_input.html
@@ -2899,6 +2899,16 @@
               The file containing the code to be modified.
             </p>
           </field>
+          <field name="fileStamp">
+            <ref>long</ref>
+            <p>
+              The modification stamp of the file at the moment when the change
+              was created, in milliseconds since the "Unix epoch". Will be -1 if
+              the file did not exist and should be created. The client may use
+              this field to make sure that the file was not changed since then,
+              so it is safe to apply the change.
+            </p>
+          </field>
           <field name="edits">
             <list><ref>SourceEdit</ref></list>
             <p>