When we enter a multibyte character in an editable ComboBox,
both of the character and one-byte character is inputted.
This problem dosen't occurs when using Windows + Java7u10.

Environment:
MacOS10.7,10.8
Java7u10

Steps to Reproduce:
1. Enter a Japanese character in an editable ComboBox(a one-byte character is input at this point）.
2. Press the Enter Key to confirm the entry.
3. Both of the Japanese character and the one-byte character are shown in the editable ComboBox.

Source Code:
      <HBox id="HBox" alignment="CENTER_LEFT" spacing="5.0">
        <children>
          <VBox id="VBox" alignment="CENTER" spacing="0.0">
            <children>
              <AnchorPane id="AnchorPane" minHeight="-Infinity" minWidth="-Infinity" prefWidth="-1.0">
                <children>
                  <HBox id="HBox" alignment="CENTER" layoutY="1.0" spacing="30.0">
                    <children>
                      <ComboBox fx:id="comboOne" editable="true" prefWidth="54.0">
                        <items>
                          <FXCollections fx:factory="observableArrayList">
                            <String fx:value="ITEM1" />
                            <String fx:value="ITEM2" />
                            <String fx:value="ITEM3" />
                          </FXCollections>
                        </items>
                      </ComboBox>
                    </children>
                  </HBox>
                </children>
              </AnchorPane>
              <AnchorPane id="AnchorPane" minHeight="-Infinity" minWidth="-Infinity" prefWidth="170.0">
                <children>
                  <HBox id="HBox" alignment="CENTER" layoutY="1.0" spacing="30.0">
                    <children>
                      <ComboBox fx:id="comboTwo" editable="true" prefWidth="54.0">
                        <items>
                          <FXCollections fx:factory="observableArrayList">
                            <String fx:value="ITEM1" />
                            <String fx:value="ITEM2" />
                            <String fx:value="ITEM3" />
                          </FXCollections>
                        </items>
                      </ComboBox>
                    </children>
                  </HBox>
                </children>
              </AnchorPane>
            </children>
          </VBox>
        </children>
      </HBox>