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Desde la última versión (?) De Firefox Nightly (35.0a1) he tenido un problema context-overflow: ellipsis dentro de un contenedor flexbox conflex-direction: row, con cada columna de 50% de ancho.

Manifestación:

.container {
  width: 300px;
  background: red;
}

.row {
  display: flex;
  flex-direction: row;
  flex-wrap: wrap;
}

.column {
  flex-basis: 50%;
}

.column p {
  background: gold;
  
  /* Will not work in Firefox Nightly 35.0a1 */
  text-overflow: ellipsis;
  overflow: hidden;
  white-space: nowrap;
}

<div class="container">
  <div class="row">
    <div class="column">
      <p>Captain's Log, Stardate 9529.1: This is the final cruise of the starship Enterprise under my command. This ship and her history will shortly become the care of another crew. To them and their posterity will we commit our future. They will continue the voyages we have begun and journey to all the undiscovered countries boldly going where no man, where no one has gone before.</p>
    </div>
    <div class="column">
      <p>Captain's Log, Stardate 9529.1: This is the final cruise of the starship Enterprise under my command. This ship and her history will shortly become the care of another crew. To them and their posterity will we commit our future. They will continue the voyages we have begun and journey to all the undiscovered countries boldly going where no man, where no one has gone before.</p>
    </div>
  </div>
</div>

En Nightly, el texto se filtrará fuera de su contenedor y no agregará... al final. En Chrome y Firefox Stable funciona según lo previsto.