[FIX] mail: composer fixes

- chatter composer did incorrectly send messages when enter is pressed
- add a div around the textareas to prevent rendering issues because of
  flex

addons/mail/static/src/js/chatter.js

@@ -467,6 +467,10 @@ var ChatterComposer = composer.BasicComposer.extend({
         return $.when(this._super.apply(this, arguments), this.message_get_suggested_recipients());
     },
 
+    should_send: function () {
+        return false;
+    },
+
     preprocess_message: function () {
         var self = this;
         var def = $.Deferred();

addons/mail/static/src/js/composer.js

@@ -315,7 +315,7 @@ var BasicComposer = Widget.extend({
     template: "mail.ChatComposer",
 
     events: {
-        "keydown .o_composer_input": "on_keydown",
+        "keydown .o_composer_input textarea": "on_keydown",
         "keyup .o_composer_input": "on_keyup",
         "change input.o_form_input_file": "on_attachment_change",
         "click .o_composer_button_send": "send_message",
@@ -367,7 +367,7 @@ var BasicComposer = Widget.extend({
 
         this.$attachment_button = this.$(".o_composer_button_add_attachment");
         this.$attachments_list = this.$('.o_composer_attachments_list');
-        this.$input = this.$('.o_composer_input');
+        this.$input = this.$('.o_composer_input textarea');
         this.$input.focus(function () {
             self.trigger('input_focused');
         });

addons/mail/static/src/less/client_action.less

@@ -128,9 +128,11 @@
 
                 .o_composer_input {
                     .o-flex(1, 1, auto);
-                    padding: 5px;
                     margin-right: 5px;
-                    border: none;
+                    > textarea {
+                        padding: 5px;
+                        border: none;
+                    }
                 }
                 &.o_extended_composer .o_composer_input {
                     margin-right: 0;

addons/mail/static/src/less/composer.less

@@ -10,7 +10,7 @@
 }
 
 .o_composer {
-    .o_composer_input {
+    .o_composer_input > textarea {
         resize: none;
     }
 }

addons/mail/static/src/xml/composer.xml

@@ -14,7 +14,9 @@
              </div>
          </t>
          <div t-attf-class="o_composer #{widget.extended ? 'o_extended_composer' : ''}">
-             <textarea class="o_composer_input" placeholder="Write something..."/>
+             <div class="o_composer_input">
+                 <textarea placeholder="Write something..."/>
+             </div>
              <t t-if="!widget.extended">
                  <div class="btn-group o_composer_buttons">
                     <button class="btn btn-sm btn-primary o_composer_button_send" type="button"><t t-esc="widget.options.send_text"/></button>