patch(thread-list): Limit number of injected icons in narrow mode to 1

- Update InjectedComponentSet to take a limit for the amount of matching
  components to render

internal_packages/thread-list/lib/thread-list-columns.cjsx

@@ -6,7 +6,6 @@ classNames = require 'classnames'
  RetinaImg,
  MailLabelSet,
  MailImportantIcon,
- InjectedComponent,
  InjectedComponentSet} = require 'nylas-component-kit'
 
 {Thread, FocusedPerspectiveStore, Utils} = require 'nylas-exports'
@@ -114,17 +113,20 @@ cNarrow = new ListTabular.Column
     if hasDraft
       pencil = <RetinaImg name="icon-draft-pencil.png" className="draft-icon" mode={RetinaImg.Mode.ContentPreserve} />
 
+    # TODO We are limiting the amount on injected icons in narrow mode to 1
+    # until we revisit the UI to accommodate more icons
     <div style={display: 'flex', alignItems: 'flex-start'}>
       <div className="icons-column">
         <ThreadListIcon thread={thread} />
         <InjectedComponentSet
-          key="injected-component-set"
           inline={true}
+          matchLimit={1}
           direction="column"
           containersRequired={false}
+          key="injected-component-set"
+          exposedProps={thread: thread}
           matching={role: "ThreadListIcon"}
           className="thread-injected-icons"
-          exposedProps={thread: thread}
         />
         <MailImportantIcon
           thread={thread}

src/components/injected-component-set.cjsx

@@ -40,6 +40,7 @@ class InjectedComponentSet extends React.Component
    - `matching` Pass an {Object} with ComponentRegistry descriptors
       This set of descriptors is provided to {ComponentRegistry::findComponentsForDescriptor}
       to retrieve components for display.
+   - `matchLimit` (optional) A {Number} that indicates the max number of matching elements to render
    - `className` (optional) A {String} class name for the containing element.
    - `children` (optional) Any React elements rendered inside the InjectedComponentSet
       will always be displayed.
@@ -57,6 +58,7 @@ class InjectedComponentSet extends React.Component
     matching: React.PropTypes.object.isRequired
     children: React.PropTypes.array
     className: React.PropTypes.string
+    matchLimit: React.PropTypes.number
     exposedProps: React.PropTypes.object
     containersRequired: React.PropTypes.bool
     onComponentsDidRender: React.PropTypes.func
@@ -121,8 +123,9 @@ class InjectedComponentSet extends React.Component
 
   _getStateFromStores: (props) =>
     props ?= @props
+    limit = props.matchLimit
 
-    components: ComponentRegistry.findComponentsMatching(@props.matching)
+    components: ComponentRegistry.findComponentsMatching(@props.matching)[...limit]
     visible: ComponentRegistry.showComponentRegions()