Merge branch 'stable-2.9'
* stable-2.9:
2.9 release notes: Add warning about download commands
SideBySide2: Add syntax highlighting for 18 more languages
Use properties file to map file extensions to CM3 mime types
Conflicts:
gerrit-gwtui/src/main/java/net/codemirror/lib/ModeInjector.java
gerrit-gwtui/src/main/java/net/codemirror/mode/Modes.java
gerrit-gwtui/src/main/java/net/codemirror/mode/mode_map
gerrit-server/src/main/resources/com/google/gerrit/server/mime-types.properties
lib/codemirror/cm3.defs
Change-Id: I9c95ad442cd44b8fcd6b73baef9f7129e197cb9f
