[turbofan] Reduce boilerplate around HeapNumber allocation in stubs.

src/compiler/code-stub-assembler.h

Index: src/compiler/code-stub-assembler.h
diff --git a/src/compiler/code-stub-assembler.h b/src/compiler/code-stub-assembler.h
index b380aedc15309ef0fc5f443bf2f837612668a143..43014196b736efdc11efb1d45a1b5dfd53b98830 100644
--- a/src/compiler/code-stub-assembler.h
+++ b/src/compiler/code-stub-assembler.h
@@ -305,7 +305,11 @@ class CodeStubAssembler {
   Node* LoadFixedArrayElementConstantIndex(Node* object, int index);
 
   // Allocate an object of the given size.
-  Node* Allocate(int size, AllocationFlags flags);
+  Node* Allocate(int size, AllocationFlags flags = kNone);
+  // Allocate a HeapNumber without initializing its value.
+  Node* AllocateHeapNumber();
+  // Allocate a HeapNumber with a specific value.
+  Node* AllocateHeapNumberWithValue(Node* value);
 
   // Store an array element to a FixedArray.
   Node* StoreFixedArrayElementNoWriteBarrier(Node* object, Node* index,