Take care fall-through cases of switch in pdfium

Found with Clang's -Wimplicit-fallthrough option by tzik@chromium.org.

R=thestig@chromium.org

Review URL: https://codereview.chromium.org/1549283002 .
diff --git a/fpdfsdk/src/formfiller/FFL_FormFiller.cpp b/fpdfsdk/src/formfiller/FFL_FormFiller.cpp
index 2e0451c..ae99edb 100644
--- a/fpdfsdk/src/formfiller/FFL_FormFiller.cpp
+++ b/fpdfsdk/src/formfiller/FFL_FormFiller.cpp
@@ -273,8 +273,10 @@
     case FIELDTYPE_CHECKBOX:
     case FIELDTYPE_RADIOBUTTON:
       bDestroyPDFWindow = TRUE;
+      break;
     default:
       bDestroyPDFWindow = FALSE;
+      break;
   }
   EscapeFiller(pPageView, bDestroyPDFWindow);
 }
diff --git a/fpdfsdk/src/javascript/JS_GlobalData.cpp b/fpdfsdk/src/javascript/JS_GlobalData.cpp
index 474886c..4d6edc8 100644
--- a/fpdfsdk/src/javascript/JS_GlobalData.cpp
+++ b/fpdfsdk/src/javascript/JS_GlobalData.cpp
@@ -51,13 +51,13 @@
         pNewObjData->nType = pOldObjData->nType;
         pNewObjData->objData.Copy(pOldObjData->objData);
         Add(pNewObjData);
-      }
+      } break;
       case JS_GLOBALDATA_TYPE_NULL: {
         CJS_KeyValue* pNewObjData = new CJS_KeyValue;
         pNewObjData->sKey = pOldObjData->sKey;
         pNewObjData->nType = pOldObjData->nType;
         Add(pNewObjData);
-      }
+      } break;
     }
   }
 }