fix(win32-styling): Buttons, popovers have hard corners on windows

static/components/button-dropdown.less

@@ -108,3 +108,15 @@
     background-color: @text-color;
   }
 }
+
+body.platform-win32 {
+  .button-dropdown {
+    .primary-item {
+      border-radius: 0;
+    }
+    .secondary-picker,
+    .secondary-items {
+      border-radius: 0;
+    }
+  }
+}

static/components/popover.less

@@ -41,3 +41,15 @@
     background-color: @background-color;
   }
 }
+
+body.platform-win32 {
+  .popover {
+    border-radius: 0;
+  }
+  .menu {
+    .header-container,
+    .footer-container {
+      border-radius: 0;
+    }
+  }
+}

static/workspace.less

@@ -336,6 +336,10 @@ body.platform-win32 {
     order: -101;
   }
 
+  .btn {
+    border-radius: 0;
+  }
+  
   .flexbox-handle-vertical {
     cursor:ns-resize;
   }