Reduce how often we call FindDexCache

Before host boot.oat -j4 optimizing compile:
real  1m17.792s
user  3m26.140s
sys 0m8.340s

After:
real  1m12.324s
user  3m22.718s
sys 0m8.320s

Change-Id: If18e9e79e06cdf1676692e5efacb682bf93889c3
diff --git a/compiler/optimizing/builder.cc b/compiler/optimizing/builder.cc
index 23ab94e..1650fd1 100644
--- a/compiler/optimizing/builder.cc
+++ b/compiler/optimizing/builder.cc
@@ -1205,7 +1205,8 @@
         resolved_field->GetOffset(),
         resolved_field->IsVolatile(),
         field_index,
-        *dex_file_));
+        *dex_file_,
+        dex_compilation_unit_->GetDexCache()));
   } else {
     current_block_->AddInstruction(new (arena_) HInstanceFieldGet(
         current_block_->GetLastInstruction(),
@@ -1213,7 +1214,8 @@
         resolved_field->GetOffset(),
         resolved_field->IsVolatile(),
         field_index,
-        *dex_file_));
+        *dex_file_,
+        dex_compilation_unit_->GetDexCache()));
 
     UpdateLocal(source_or_dest_reg, current_block_->GetLastInstruction());
   }
@@ -1334,14 +1336,16 @@
                                                                 resolved_field->GetOffset(),
                                                                 resolved_field->IsVolatile(),
                                                                 field_index,
-                                                                *dex_file_));
+                                                                *dex_file_,
+                                                                dex_cache_));
   } else {
     current_block_->AddInstruction(new (arena_) HStaticFieldGet(cls,
                                                                 field_type,
                                                                 resolved_field->GetOffset(),
                                                                 resolved_field->IsVolatile(),
                                                                 field_index,
-                                                                *dex_file_));
+                                                                *dex_file_,
+                                                                dex_cache_));
     UpdateLocal(source_or_dest_reg, current_block_->GetLastInstruction());
   }
   return true;