Simplify chunk counting logic

Author: ericrosenbaum

src/containers/sound-editor.jsx

@@ -272,8 +272,8 @@ class SoundEditor extends React.Component {
         const startIndex = this.state.trimStart === null ?
             0 : Math.floor(this.state.trimStart * numChunks);
         const endIndex = this.state.trimEnd === null ?
-            numChunks - 1 : Math.floor(this.state.trimEnd * numChunks);
-        const trimChunks = this.state.chunkLevels.slice(startIndex, endIndex + 1);
+            numChunks - 1 : Math.ceil(this.state.trimEnd * numChunks);
+        const trimChunks = this.state.chunkLevels.slice(startIndex, endIndex);
         return Math.max(...trimChunks) > MAX_RMS;
     }
     getUndoItem () {