CodeMirror: Force inputStyle to be "textarea"

As of version 5.8, CodeMirror defaults inputStyle to
"contenteditable" on mobile browsers. With that, CodeMirror
grabs focus every time one tries to write an inline comment,
making the commenting functionality unusable on mobile.

There might be some upstream issue involved, but for now let's
just set inputStyle to "textarea" as CodeMirror already does on
desktop browsers. This will make commenting usable on mobile
again.

Change-Id: I278d6bfc671e77f9a02d21b2894649e0d9885a5c

gerrit-gwtui/src/main/java/com/google/gerrit/client/diff/SideBySide.java

@@ -242,6 +242,7 @@ CodeMirror newCm(
     return CodeMirror.create(parent, Configuration.create()
       .set("cursorBlinkRate", prefs.cursorBlinkRate())
       .set("cursorHeight", 0.85)
+      .set("inputStyle", "textarea")
       .set("keyMap", "vim_ro")
       .set("lineNumbers", prefs.showLineNumbers())
       .set("lineWrapping", false)

gerrit-gwtui/src/main/java/com/google/gerrit/client/diff/Unified.java

@@ -234,6 +234,7 @@ CodeMirror newCm(
         .set("cursorBlinkRate", prefs.cursorBlinkRate())
         .set("cursorHeight", 0.85)
         .set("gutters", gutters)
+        .set("inputStyle", "textarea")
         .set("keyMap", "vim_ro")
         .set("lineNumbers", false)
         .set("lineWrapping", false)