Fix some style issues

BUG=angleproject:2123

Change-Id: Ic3c70c7148297662d4fd9e08edcd208f5a1cc885
Reviewed-on: https://chromium-review.googlesource.com/601370
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
diff --git a/src/libANGLE/ResourceManager.cpp b/src/libANGLE/ResourceManager.cpp
index 7a49181..6f5bd50 100644
--- a/src/libANGLE/ResourceManager.cpp
+++ b/src/libANGLE/ResourceManager.cpp
@@ -272,7 +272,7 @@
     return AllocateEmptyObject(&mHandleAllocator, &mObjectMap);
 }
 
-Renderbuffer *RenderbufferManager::getRenderbuffer(GLuint handle)
+Renderbuffer *RenderbufferManager::getRenderbuffer(GLuint handle) const
 {
     return mObjectMap.query(handle);
 }
@@ -298,12 +298,12 @@
     return AllocateEmptyObject(&mHandleAllocator, &mObjectMap);
 }
 
-Sampler *SamplerManager::getSampler(GLuint handle)
+Sampler *SamplerManager::getSampler(GLuint handle) const
 {
     return mObjectMap.query(handle);
 }
 
-bool SamplerManager::isSampler(GLuint sampler)
+bool SamplerManager::isSampler(GLuint sampler) const
 {
     return mObjectMap.contains(sampler);
 }
@@ -325,7 +325,7 @@
     return handle;
 }
 
-FenceSync *FenceSyncManager::getFenceSync(GLuint handle)
+FenceSync *FenceSyncManager::getFenceSync(GLuint handle) const
 {
     return mObjectMap.query(handle);
 }